Ogabi - native
Captain Paul d’Arnot
Helen Gregory - heroine
Gregory - Helen’s father
Lal Taask - henchman
Magra - Anglo-Indian girl
Atan Thome - East Indian
Wolff - white hunter
Wong Feng - shop owner
Lt. Lavac - pilot
Dr. Dillinger - (mentioned)
Baby Face Nelson - (mentioned)
Chemungo - son of Mpingu
Mpingu - chief of the Buiroos
Buiroos - cannibal tribe
monkeyman - name for Tarzan
Mbuli - headman Thome safari
Ungo - king ape
Dr.Jekyll/Mr. Hyde - mentioned
Atka - Queen of Ashair
Akamen - Nobleman of Ashair
Thetan- nephew of Thobos
Herat - King of Thobos
Brulor - god, Father of Diamonds
Zytheb - Keeper of the Keys
Herkuf - imprisoned Ashair priest
Mentheb - Queen of Thobos
Memet - famous Thobos warrior
ptomes - Ashair priests & fishermen
Mesnek - Queen Mentheb’s servant
Isis - goddess of the Asharians
Horus - god of the Asharians
Chon - god of Thobos
Klu Klux Klan - mentioned
Zu-tho - great ape
Ga-un - great ape
Gilbert and Sullivan - mentioned
Loango - seaport of the Congo
Bonga - Northern Rhodesia outpost
Wong Feng’s Shop
Tuen-Baka - volcano
Lake Horus - inside Tuen-Baka
Temple of Brulor - at Lake Horus
Temple of Chon - inside cave
Hollywood - mentioned
planter’s punches - beverage
Father of Diamonds
Gregory’s map to Ashair
metal sole shoes
EDGAR RICE BURROUGHS'
Tarzan and the Forbidden City
Summary and Introduction by Duane Adams
David Bruce Bozarth, Managing Editor
Copyright © 2001
"Forbidden City" is generally considered a rather weak Tarzan story by dedicated and oft-times critical readers because the original tale came from a radio serial written by Rob Thompson. Burroughs’ heart was apparently not into revising "Tarzan and the Forbidden City" for magazine and book publication. Burroughs teams his ape-man up with his old friend d’Arnot, who explains the history of Tarzan to the characters and to the reader. The author initially uses a case of mistaken identity between Tarzan and Brian Gregory but this plot device is soon abandoned. "Forbidden City" is a tale of treachery, deceit, greed,--and trust and love. The novel contains Burroughs' trademarks of capture and escape, unrequited love, and heroic deeds. Burroughs’ prose has been better in other Tarzan novels, but as one of the middle tales where plot redundancy and lost cities seem to stand shoulder to shoulder, "Forbidden City" is nonetheless a required item for the completist.
"The Red Star of Tarzan" was published as a six part serial in Argosy Weekly, March 19, 26; April 2, 9, 16, 23, 1938. The story is a revised version of the radio serial, "Tarzan and the Diamond of Asher," written by Rob Thompson in 1934. The book version is significantly different than the magazine story. Burroughs also wrote a continuity story line of this story for the daily newspaper comic strip, which ran before the magazine story was published. It is Burroughs' fifty-first hardback book and the twentieth Tarzan novel. The first edition published by Burroughs Inc. features dust jacket and illustrations by John Coleman Burroughs. A paperback reprint by Bantam Books in 1940 is the first Burroughs paperback book. Tarzana, Whitman, and Ballantine have done reprints. The old Burroughs Bulletin published a reprint of the magazine version.
Robert B. Zeuschner’s The Exhaustive Scholar’s and Collector’s Descriptive Bibliography.
Tarzan relaxes on Tantor. He senses a Gomangani. Ogabi, a native, brings a message from a man named Gregory and Paul d’Arnot for him to come to the village of Loango. Tarzan leaves for the port city. Helen Gregory asks Captain d’Arnot if he thinks Tarzan can find her brother Brian, who has been being missing for three years. Gregory--Brian and Helen’s father--thinks his son may be dead.
D’Arnot cautions Gregory to not offer Tarzan money for the job. Lal Taask, an East Indian, and Magra, an Anglo-Indian, drink Planter’s Punches and try to figure a way to get close to the Gregorys. Tarzan enters. Helen thinks he is her brother Brian. Lal Taask and Magra also think Tarzan is Brian. Magra sends a message to Tarzan asking him to meet her by the entrance. When Tarzan arrives she calls him Brian Gregory. Tarzan says she is mistaken and turns to leave. She warns that Lal Taask has a pistol at his back and they go upstairs, passing the Gregorys and d’Arnot. Entering a room where Atan Thome, an East Indian, awaits, Thome wants to buy the map to Ashair, the Forbidden City. Tarzan says he has never heard of Ashair. Thome, furious, commands Lal Taask to kill Tarzan.
D’Arnot wonders why Tarzan went upstairs. Lal Taask attacks Tarzan. Tarzan throws him to the floor and turns on Atan Thome. The East Indian says he only wants the map to Ashair and the Father of Diamonds. Thome pulls a pistol. Magra intercedes. Thome pulls Magra into another room. The sound of a gunshot brings d’Arnot and the Gregorys to the room. Tarzan explains the situation and crashes into the next room. The room is empty. Lal Taask also disappears when the others go into the room. D’Arnot is attracted to Helen Gregory. Tarzan asks them about the map Atan Thome is seeking. Helen says she has a sketchy map her brother sent to her. D’Arnot tells Tarzan about the Gregory's safari plans. Tarzan agrees to lead the safari. A guide named Wolff is hired as a hunter. Behind Wong Feng’s shop Thome questions Magra why she stopped him from shooting Brian (Tarzan). Magra whispers her plan to Thome. Thome replies that Lal Taask shall do it tomorrow. Wong Feng, the Chinese herbalist, nurses Lal Taask back to health.
The Gregorys introduce Wolff to Tarzan. Wolff is upset about being replaced as safari leader, but he will take the job as hunter. He leaves but returns shortly asking to see the map of their route. He wants to take the map with him. Gregory says no and replaces the map in Helen’s dresser drawer. After lunch Helen goes shopping alone in the Loango’s bazaar, much to the dismay of d’Arnot. As she enters Wong Feng’s shop, Lal Taask grabs her and pulls her into a back room. Atan Thome announces that he will hold her until he gets the map to Ashair. He threatens her with slavery and dictates a ransom note. That evening, because Helen has not returned, Tarzan and d’Arnot go to look for her. They return without her. A note tied to a rock crashes through the window. The note demands the map in exchange for Helen. Gregory goes to the drawer to retrieve the map. It is gone.
Wolff copies the map and plots his revenge. Lal Taask returns to Feng’s shop with the report that the map has been stolen. Wolff comes to Atan Thome and offers to sell him the map for five hundred pounds and one half share in the diamond. Thome pays him and wants him to lead the Gregory safari astray as Magra infiltrates the safari. Wolff agrees and leaves. Thome makes plans to leave immediately with Helen as hostage. He instructs Magra to join the Gregory safari at any cost. Magra warns him not to harm Helen. Magra goes to the Gregorys and explains that Thome has taken Helen up river to Bonga. They fear that Thome has too large of a head start. D’Arnot suggests taking a naval seaplane to Bonga; thus, they would arrive before Thome.
Tarzan’s party takes off for Bonga with Lt. Lavac as their pilot. Although the sky is clear, Tarzan predicts a storm. During the storm the fuel line clogs. Wolff panics. Tarzan calms him. They break out of the storm and spy a lake to land upon. Because of the storm and a leaky fuel tank, they are lost and out of fuel.
Tarzan’s group marches for four days. The ape-man is convinced he knows where they are and proceeds after Thome. Magra wanders away from the camp. A lion stalks her. Tarzan’s senses alert him to the danger. He swings through the tress, lands on numa, kills it, and gives the victory cry of the bull ape. Magra realizes this is not Brian Gregory and falls for Tarzan. They return to camp. Tarzan says they will find Brian and that he is not interested in the diamond. Thome has taken the Gregory’s safari porters out of Bonga. Helen compares Thome to Dillinger and Baby Face Nelson. Thome eyes Helen with evil intent. Lal Taask warns him about the white man’s power. That night, Thome approaches Helen’s tent. She sees him coming and leaves by the back of the tent. She heads into the forest. In the morning she realizes that she is lost but presses onwards.
Chemungo, son of Mpingu, chief of the Buiroos and three warriors see Helen walking across a clearing. Shouting, the Buiroos run towards her. Helen retreats into the trees. A lion emerges in front of her. While attempting to escape, Helen trips and falls. The Buiroos kill the lion and drag Helen to their village. Mpingu, the chief of the cannibal tribe, declares they will feast tonight. Tarzan knows the way to Bonga. Wolff says for one thousand pounds and one half share of the diamond, he will lead them to Ashair. Tarzan calls him a crook. Wolff cold cocks Tarzan. Tarzan is about to kill Wolff when Gregory agrees to the price so that he can find his son and daughter. Magra accuses Wolff to betraying Thome. Wolff returns her threats. Tarzan leaves camp to reconnoiter. The next day, after giving up on finding a village, Tarzan hears drums.
Drums beat as the Buiroos tie Helen to a stake. Mbuli, headman of the Thome safari, informs Thome that they are in cannibal country. Thome decides to abandon searching for Helen. Lal Taask tells Thome that her blood is on his hands. D’Arnot informs the party that the drums are probably from a cannibal tribe. Tarzan proceeds towards the drums with the thought of frustrating the Gomangani in their ritual. Thome pushes onwards towards Ashair. Lal Taask plans to kill Wolff if he catches up with the safari. D’Arnot and Wolff argue about Tarzan’s importance to the safari. The drums stop. Tarzan enters the village of Mpingu and climbs a tree overlooking the main street. He recognizes Helen and kills a native with an arrow. The drums stop. Tarzan gives the victory cry of the bull ape. D’Arnot and the others hear Tarzan’s victory cry. Mbuli tells Thome about Tarzan. Thome fears the cry they heard may be from the ape-man. Tarzan shouts that he is a demon who has come for the memsahib. He drops to Helen’s side. Chemungo attacks Tarzan. Tarzan grabs the son of the chief and raises him over his head. He demands that they open the gates.
Mpingu has the gates opened. Tarzan and Helen leave. As they head back to the Gregory camp, they relate their stories to each other. Magra hints to d’Arnot that she is bound by an oath. Tarzan and Helen enter the camp. Helen tells her tale of capture. Lavac is infatuated with Helen. Tarzan tells Gregory that he will be gone a few days. He leaves. D’Arnot and Wolff fight over Tarzan’s intentions. On the trail, Lavac professes his love to Helen. Helen rejects him. Lavac becomes jealous of d’Arnot. Wolff makes advances to Magra. She rejects him. Wolff gets angry. Tarzan returns with the news of Thome’s trail. He informs them that Wolff was leading them astray. They decide to allow Wolff to continue with them.
Thome and Taask approach Tuen-Baka, the volcano that holds the city of Ashair. Thome tells Lal Taask the story about how he loved Magra’s mother, a maharaja. She married an Englishman, who went to Ashair. He was captured, tortured, but managed to escape. Thome feels that part of the Father of Diamonds is rightfully Magra’s because of the suffering of her father. Mbuli states that the porters will go no further because of the taboos of Tuen-Baka. In the morning, the porters have deserted with all the equipment. Thome has a burst of megalomania. Despite Lal Taask’s objections, they climb the volcano. That night, a sepulchral voice speaks to them.
Ungo, the king ape, senses gomangani and tarmangani he could use for sacrifice at the Dum-Dum. Ungo’s tribe attacks the Gregory safari. D’Arnot manages to shoot one ape. The apes carry Magra to the Dum-Dum clearing. The Gregory party is in disarray when Tarzan returns. Tarzan tells them to continue on the trail. He will go after Magra. He reaches the Dum-Dum just before the kill. Ungo challenges Tarzan’s presence. During the fight Magra thinks of Tarzan as a primitive Dr. Jekyll/Mr. Hyde. Tarzan puts a full Nelson on Ungo. D’Arnot explains the Dum-Dum rites to the Gregory party. Tarzan forces Ungo to surrender. Ungo bellows, “Kreegah,” which means I surrender. (The editor is mistaken about the ape/English translation. Kreegah means danger or beware. Kagoda means surrender.) Tarzan becomes king of the tribe. Magra does not understand what has happened.
The voice and apparition of the night forces Thome and Taask to return to Bonga for reinforcements. They are captured by white warriors and taken aboard an open galley. Thome believes they are being taken to the Forbidden City. D’Arnot expresses his love to Helen. She is not receptive to his confession. Tarzan and Magra enter the camp with the tribe of apes. Tarzan tells them that the apes will accompany them. Wolff doesn’t like it. That night, Lavac again speaks about his love to Helen. She rejects him. Wolff presses advances on Magra. She rejects him. Wolff threatens to get Magra.
Thome and Taask are taken by barge through a Stygian dark tunnel to the interior of Tuen-Baka. Ashair is in front of them. Thobos, another city, is at the far end of the lake. At the bottom of the lake they see a temple and men walking under water. They are taken to an official, who tells them their fate rests with the Queen. Thome requests an audience with the Queen. They are placed in a dungeon with little food. After many days, they are brought before the Queen. A description of Atka, Queen of Ashair, is given. Thome weaves a tale of a large force moving on Ashair. The Queen places the prisoners under the charge of Akamen, an Ashair nobleman. They are given freedom within the city except for the royal wing and the underwater temple. Thome expresses desire to see the temple from the lakeside. Akamen tells him that could be fatal.
Mbuli leads the deserting porters away from the volcano. Tarzan stops them and commands them to accompanying them to Tuen-Baka. Unwillingly the porters join the safari. At the volcano, Tarzan scouts out the area. He discovers a white warrior facing a small Tyrannosaurus Rex. Tarzan drops on its back and uses his knife. The warrior and Tarzan kill the T-Rex. Thetan of Thobos introduces himself in Swahili. Tarzan tells him they are going to Ashair. Thetan explains that Thobos is the enemy of Ashair. He suggests going to his uncle Herat, Thobotian King, to ask if Tarzan’s party can come to Thobos. Thetan knows a secret way into the volcano. Back at the camp, Thetan tells the Gregory party the history of the area. Floating death heads warn them to leave. Tarzan attacks. The Asharians attack but leave after a few gunshots. Tarzan captures a death head to prove to the porters that the apparitions are human. Tarzan releases the prisoner with the message to let Brian Gregory go. As he leaves, the Asharian says no one leaves the Forbidden City. Helen is missing. They rush to the river in time to see a galley pulling away with Helen onboard. Thetan informs them that Helen will probably become a handmaiden to priests. Tarzan gives the cry of the bull ape. Tarzan, d’Arnot, and Thetan follow the galley in the hopes they will camp on this side of the volcano tunnel. The apes join them. D’Arnot commiserates about Helen.
During the night, Wolff conspires with Mbuli to desert the safari and take Magra with them. At dawn, Helen sees Tarzan’s rescue party approaching the Asharians. An Asharian raises the alarm and drags Helen towards the galley. D’Arnot kills Helen’s captor. Tarzan and the apes kill all the Asharians except one. The warrior advances on d’Arnot. Tarzan kills him with a spear throw. He forces the slaves to row the galley down river to their encampment. Helen and d’Arnot snuggle. They arrive to learn that Wolff, Magra, and the porters have deserted. Tarzan purposes that they use the galley under the cover of night to slip by Ashair and head for Thobos. A warrior reports the galley incident to Queen Atka. She sends six galleys to deal with the intruders.
During a rest break, Wolff attempts to manhandle Magra. She manages to draw his revolver and kill him. She forces Mbuli and his men to head back to the Gregory camp. D’Arnot and Lavac scuffle over Helen. Tarzan intervenes. Magra herds the porters into the camp. After the supplies are loaded onto the galley, Tarzan gives the porters a choice of joining them or leaving. During the trip upriver, Magra pledges loyalty to Tarzan. They spy six galleys approaching. Resistance is futile. An Asharian galley smashes into Tarzan’s ship. It sinks. The other Asharian galleys pick up the survivors and heads to Ashair. Helen and d‘Arnot are on a ship together. They hear an eerie scream.
Akamen tells Thome and Taask that the enemy has probably been captured. He explains that Brulor is their god, the Father of Diamonds and that his temple is at the bottom of Lake Horus. Both Brulor and the diamond share the name Father of Diamonds. They hear the sound of an ape. Tarzan tells Lavac about his plan. In the tunnel, Tarzan screams and throws men overboard. All the prisoners join the melee. Thetan shouts to the galley slaves to join them also. They do. In the other boat Helen and d’Arnot realize that Tarzan has started a revolt. Helen professes her love to d’Arnot. Ogabi is killed during the rebellion. Tarzan’s people head for Thobos. Upon landing, Thetan is arrested for bringing strangers to Thobos.
Helen and d’Arnot are brought before the Queen who has Thome and Taask next to her. Atka accuses them of plotting to steal the diamond. Thome and d’Arnot argue over who is telling the truth. The Queen has d’Arnot thrown in a cage and Helen brought to the priests to become a handmaiden. Akamen intercedes for Thome and Taask. D’Arnot is taken to the underwater temple via a crude elevator. An old man, Brulor, instructs Zytheb, a priest, to place Paul in a cage. In the cage next to him, d’Arnot discovers Brian Gregory. He tells him about their rescue safari. Brian explains about the duality of the Father of Diamonds. He also points out Herkuf, an imprisoned priest. Helen is anointed with oils and taken to the temple. Brulor doesn’t believe that she comes from a place called America. Brulor performs a rite over Helen and Zytheb, the Keeper of the Keys. Brulor declares them married. Brian and d’Arnot are beside themselves with disbelief.
Tarzan, Thetan, Gregory, Lavac, and Magra are brought before King Herat and Queen Mentheb. Thetan tells the King the tale of his rescue. The King decides to let them live, if they kill an Asharian warrior, kill a lion, and bring him the Father of Diamonds. Magra is turned over to the women. The men are imprisoned. Akamen informs Thome and Taask that if his cousin the Queen should die, he would be king and grateful to the outsiders. In the morning, Tarzan volunteers to fight the Asharian warrior. In the arena the warrior boasts of killing Memet, a famous Asharian warrior. A terrific battle ensues. The warrior becomes so frighten that Tarzan will tear him apart that he commits suicide with his knife. Herat gives Tarzan his freedom. Tarzan asks about Magra. The Queen is taken with Tarzan. Tarzan offers to fight the lion. The Queen expresses concern about Tarzan. The King is upset by the Queen’s reaction, and grants Tarzan’s request.
Brian and d’Arnot commiserate over Helen. A ‘ptome,’ a lesser priest, enters wearing a diving helmet and weighted boots. They enter Lake Horus through a watertight compartment and spear fish for the prisoners with a trident. The fish are eaten raw. Zytheb takes Helen to his apartment and tries to kiss her. Helen hits him over the head with a vase, killing him. She hides his body in a closet and takes his keys and knife. Helen makes it back to the throne room and releases d’Arnot. She tells Paul that she has killed Zytheb. Paul releases Brian. They release the other prisoners and convince Herkuf, the defrocked priest, to show them the secret passage out. He leads them through a dark tunnel and exit onto a hill above Ashair. A Thobotian prisoner says he can guide them out of Tuen-Baka. Herkuf knows of a canyon where they can hide during the day.
King Herat enters Magra’s room and takes her in his arms. Magra pulls out the King’s knife and threatens to tell the Queen. He backs down. The bored Queen Mentheb sends her servant, Mesnek, to bring her Tarzan. The servant comes for Tarzan. Thetan warns Tarzan to be discrete while with the Queen. The Queen is coy with Tarzan. She screams, “Isis,” as the King enters. Tarzan says he came to see the King but found the Queen. Herat doesn’t believe him and sentences him to face two lions. The next day at the arena, the King and Queen trade insults about their dalliances. The lions enter the arena. One charges Tarzan. The ape-man jumps to one side, leaps behind it, seizes it, and swings it into the face of the second charging lion. The two lions attack each other. Mentheb leans over the parapet, loses her balance, and falls into the arena. Tarzan catches her. One lion is victorious. It turns and charges Tarzan and the Queen. Tarzan kills the lion with his knife. He gives the victory cry of the bull ape. Herat is grateful to Tarzan for saving his wife. Tarzan plans to go after Brulor. Herat offers assistance, but Tarzan will go alone.
Thome is confident. Taask is worried about the assassination attempt, which he must carry out. Akamen leads Taask to the Queen’s bedroom. As the assassin raises his dagger, warriors set him upon. She has the conspirators brought to the throne room. She tells them that Thome betrayed them. She sentences all three to the cages of the temple. A list of tortures is given. In their cell Taask and Akamen rage against Thome, who thinks only about obtaining the diamond. Tarzan informs Thetan, Gregory, and Lavac that he is going to Ashair. Tarzan decides to take Lavac with him. The nine escapees from the cells make their way towards Thobos. They hear Asharian warriors following them. Tarzan and Lavac move toward Ashair. Tarzan senses people ahead and takes to the trees. The Asharians attack the escapees and capture them. A warrior threatens Helen. D’Arnot knocks him down. Another warrior is about to kill the Frenchman when Tarzan sends an arrow through his heart. He drops another warrior. The four remaining warriors fear the wrath of Atka as much as Tarzan’s arrows. A warrior wants to kill the prisoners. Tarzan finishes off the remaining four. After their stories are told, Tarzan decides that they all will return to Ashair for the Father of Diamonds and Brulor.
The Queen catches Herat in Magra’s room. She sentences her to die. Magra has a slave girl take her to Gregory’s apartment. She begs Thetan to help her escape. Thetan leads Magra and Gregory out of the city and gives them directions to Ashair. He tells them not to return. As they approach Ashair, Herkuf explains that the Father of Diamonds belongs to Thobos and their god Chon. Atka stole the diamond. He outlines a plan to get the diamond and the drunken Brulor. Tarzan will take only Herkuf in the attempt. Gregory and Magra make their way towards Ashair. They come upon three men who were part of the party that escaped from the temple. The ex-prisoners give them directions to the hidden passage of the temple. Gregory and Magra continue on their way.
Tarzan and Herkuf make it to the secret doorway. On the other side of the door, Asharian warriors prepare to trap them. Warriors also creep up upon the party on the hillside. Lavac sees them too late. They are captured. Tarzan and Herkuf are captured as well. They are brought to the temple cells. Thome is quite mad and declares the diamond is his. They are placed in a cell except for Tarzan, who is brought before the Queen. Tarzan and Atka verbally spar. Atka offers Tarzan freedom if he pledges loyalty to her. Tarzan demands freedom for his friends. Atka has him thrown back into a cage. The next day the Queen enters the temple and sentences the men to be tortured and sacrificed. Helen is to be sacrificed to Holy Horus. Ptomes dress Helen in diving gear and lead her towards the watertight compartment. The party is in despair except for Tarzan who questions Herkuf. Ungo and the apes look down into the fertile forest of Tuen-Baka. They descend to look for Tarzan.
Three ptomes take Helen into a cylindrical chamber that contains handwheels, levers, and gauges. A ptome turns the handwheel, and the chamber fills with water. Once filled, they open the outer door to the lake. They take Helen to a small circular building. Entering through the top of the dome, the building is drained of water. Helen’s suit and helmet are removed. She is forced to descend through a trap door in the floor. The ptome closes the door and the chamber begins to fill with water. Helen thinks of Paul and Brian. Tarzan bends the bars of the cage. He and Herkuf slip out. Tarzan bends the bars back. They sneak into the ptomes room and gather up three diving suits and tridents. Helen is at the top of the ladder with the water still rising. Tarzan and Herkuf make it to the death chamber and drain the water from the top chamber. A ptome awakes and discovers the missing suits and prisoners. Raising the alarm, six ptomes don their diving suits and grab tridents. Helen doesn’t recognize her rescuers as she is pulled into the air lock and forced to don a diving suit. The six ptomes catch up to the escapees as they travel away from the temple. Five of the ptomes are quickly dispatched. The sixth flees. Tarzan pursues him. During the struggle, a great fish bumps into Tarzan’s legs, knocking him over. Helen and Herkuf manage to slay the last ptome.
The discovery that Tarzan, Herkuf, and Helen are missing; plus, the discovery of the dead ptomes sends the temple of Brulor into a state of confusion. Tarzan and Herkuf take three extra diving suits with them. A huge serpent attacks them. It wraps it’s tail around Helen and swims away. Tarzan gives chase and manages to kill the snake with his knife. Herkuf joins them with the extra suits. They make it to shore. Herkuf spears a fish for their meal. Herkuf knows of a hidden boat. Under the cover of darkness, they plan to return to the temple to free their companions. Herkuf explains the history of the creation of the diving helmet, the building of the temple, and the common background of the two cities.
Magra and Gregory arrive at the secret tunnel to the outer world. They decide to hide and wait for the others to escape. They find a cave that leads to a large cavern. They go through another opening and proceed deeper and deeper into the cave. Magra gets nervous. Still deeper inside the cave someone grabs Magra and pulls her into a cavern that contains an altar. Hooded figures pull Gregory into the chamber. Gregory likens them to the Klu Klux Klan. Their captors believe they may be spies. They plan to keep them in the temple until Chon, the true god, returns.
Herkuf can’t find the hidden boat. Tarzan plans to swim across the lake and steal a boat from the Asharians. Half way across the lake a galley comes towards him. Tarzan alludes the ship by diving under water. From shore the Asharians see a light from a Thobos galley. A shark swims for Tarzan. Tarzan cuts open the shark’s belly. Breaking the surface Tarzan is pulled aboard the galley. Thetan is on the ship. Tarzan talks Thetan into picking up Herkuf and Helen and dropping them over the water temple. Six Asharian galleys search the water for the enemy. Theton’s galley picks up Tarzan’s companions and heads for Ashair. Tarzan, Herkuf, and Helen don their diving suits. Asharian galleys attempt to surround them. As the Thobos galley makes a break for freedom, Tarzan, Herkuf, and Helen jump overboard.
Herkuf becomes separated from Tarzan and Helen. They find him near the temple. Along the way Herkuf recovers a casket from a sunken galley. They decide to wait until dark before attempting to enter the temple. Meanwhile, the prisoners speculate as to the fate of Tarzan and Helen. Leaving Helen behind, Tarzan and Herkuf spear some fish and enter the temple. The ruse of the fish gets them through the ptomes chamber. A figure in a white suit swims for Helen. Tarzan bends the bars and frees the prisoners. Brian, d’Arnot, and Lavac don diving suits. Thome darts for the Father of Diamonds. The figure in white disarms Helen and pulls her towards the surface of the lake. Taask, Brian, and Gregory fight with Thome over the casket. The noise of the fight causes the ptomes to break into the room. Everyone fights with the ptomes except Thome, who escapes with the treasure. Brulor enters and calls for warriors. Herkuf kills Brulor. A ptome informs the Queen about the escape and the battle. Atka sends warriors to the temple. After the ptomes have been killed, they discover Akamen dead. Thome and Taask are missing. Brian wants to go after the diamond and Thome. Tarzan and the others head for the air chamber. Brian plays dead to let the warriors pass. Herkuf works the valves as Tarzan, d’Arnot, and Lavac face the warriors. Herkuf releases the waters of Horus into the chamber, drowning the warriors. They head for Helen’s hiding place.
The white figure drags Helen towards an underwater cave. Magra and Gregory are treated well. Helen and Chon rise from the pool in the middle of the cavern. Chon is an old man. Chon declares he will read the entrails of Gregory to see if they are telling the truth. Magra objects to the sacrifice of Gregory on the altar of Chon and the Father of Diamonds. Chon instructs his followers to treat them well until the inquisition. Thome reaches the hillside with the casket. Taask follows him with thoughts of killing his master. Brian follows both of them to get the diamond. Ungo and his tribe decides to join in the game. Ungo steals the casket as easily as stealing a wife in Hollywood. Taask chokes Thome. Brian stops him and insists that they work together to get the casket. Thome runs after Ungo. Brian regains his senses and realizes his greed almost got him killed. Ungo discards the casket. Thome throws himself on the box. Ungo goes to silence the mad Thome when he sees Brian and Taask. The apes charge the two men. They escape into a cave. The apes are distracted by the magnificence of the cave chamber.
Tarzan and his three companions find Helen missing. The casket is still there. While searching for Helen, giant seahorses with horns approach them. The seahorses attack. Tarzan kills two of them, but Lavac is killed. The remaining seahorses retreat. Tarzan, d’Arnot, and Herkuf ascend to the shore. Herkuf informs them that the casket contains the true Father of Diamonds. It was lost when Chon’s galley was sunk. Chon supposedly drown. Herkuf is positive that the return of the diamond will cause Herat to grant them any request. Herkuf travels to Thobos and presents the diamond to King Herat. Herkuf requests an attack on Ashair. War galleys leave for Ashair. Chon is about to sacrifice Gregory on the altar. Helen attempts to intercede to no avail. Tarzan watches the apes entering the cave. He and d’Arnot go to investigate. Brian and Taask stumble into the cavern and are captured by priests. The sacrifice is to continue. Tarzan and d’Arnot follow the scent of the apes through the corridors. Ungo and his apes burst into the cavern. A battle ensues. Two great apes, Zu-tho and Ga-un, grab Helen and Magra and run deep into the cave. Tarzan enters the cave temple and commands the apes to stop. Everyone stops. Zu-tho and Ga-un realize that Tarzan will probably be angry with them. They decide to kill the women and toss them into the lake. Helen and Magra leap from the cave mouth into the water. Asharians on a galley witnesses their leap.
Chon reveals that he did not die when the galley was sunk. He donned a diving suit and saved himself. Tarzan tells them about the return of the Father of Diamonds to Thobos. Chon sets them free. Tarzan, d’Arnot, and the apes search for the missing women. Helen and Magra are captured and brought before Queen Atka. In the dungeon Helen makes a joke with references to Gilbert and Sullivan. Thome wanders aimlessly with his treasure. Taask stumbles across him. Thome bashes Taask’s brains in with a rock. Zu-tho tells Tarzan that the girls jumped. Tarzan sees the galley. He plans to take the apes into Ashair. Chon and his priests will join them. Atka is informed about the approaching Thobos fleet. She orders her galleys out to meet them. Tarzan watches, as the two fleets are about to engage. Tarzan leads his crew over the walls of Ashair. The two navies clash. Tarzan forces Atka to release Helen and Magra. Magra professes her love for Tarzan. The Asharian navy is defeated. The two cities are united under King Herat and Chon. Thome is dragged into the room with his casket. It is opened to reveal a lump of coal. Thome has a heart attack and dies. Brian points out the irony of coal being referred to as the Father of Diamonds.