Unfortunately, this synopsis is almost completely wrong vis-a-vis the actual finished serial.  Only the first chapter seems to really match up, and even there there are notable discrepancies.  It appears that the serial underwent a near-complete rewrite from the treatment which was used to compose the pressbook synopsis, for reasons unknown and possibly unknowable, before it became a final shooting script.  By the end of the second chapter, the differences between pressbook and film become so great, that the only reason to really even keep the pressbook synopsis on hand is as a way to determine which published "experts" have actually seen the serial, and which have just read the synopsis in pressbook or reprint form.

Therefore, below, we are presenting the original pressbook material alongside lobby cards, and a summary of each actual serial chapter immediately below.  The serial-based synopsis, it should be noted, is not intended to be a complete, shot-for-shot workup, but also a summary of the material as it might have appeared if the real film had been used as the source of the pressbook summary instead of the abandoned screen treatment.  Where possible, we've even borrowed the wording of the pressbook to stress the (few) common points.  Also, despite the revised storyline, the serial was still printed with the chapter titles unchanged.  Finally, the synopsis for Chapter 1 is based on the entire original 65 minute cut of this chapter, not the 44 minute version edited for reissue and most commonly used for video prints today.

In the African jungles, Tarzan kills a lion and saves the life of a demented Frenchman, who tells him that D'Arnot, Tarzan's best friend is lost in the wilds of Guatemala.

Rushing to D'Arnot's aid aboard the S.S. Wangai, Tarzan accidentally meets MAJOR MARLING, an archaelogolist leading an expedition to the Guatemalan jungles in the hope of locating the famous GREEN GODDESS - a priceless Mayan relic containing a fortune in gems. He casually becomes a part of a group including ALICE MARTLING, Martling's daughter, GORDON HAMILTON, her fiance, and GEORGE,  an admirer of the Ape-Man, who has stowed aboard with Nkima, Tarzan's pet chimpanzee. ULA VALE, a mysterious woman, and RAGLAN, a racally explorer, trailing Martling to get posession of the document, dircting the expedition to the Goddess, are also passengers.

Learning that Martling has mailed the document to someone in Guatemala, the adventurers attack him in order to learn its whereabouts, but flee empty-handed when Tarzan comes to the rescue.

In Guatemala City, while Martling and Tarzan prepare for their expedition, Raglan gains possession of the document, escapes with it and starts for the jungle. They pursue him. However, Raglan, arriving at the point designated in the document, unearths the entrance to the secret underground passage leading to the lost City and the Green Goddess.

Tarzan's party arrive and enter the Lost City, only to be seized by monster servers of QUEEN MAYA, in whose court they find D'Arnot a prisoner and behold the GREEN GODDESS. Maya declares all must die save Tarzan, who may remain as her consort. Tarzan, refusing, is strapped to the altar and Maya plunges her dagger toward his heart. 

Unable to overcome her infatuation for Tarzan, Queen Maya, drops the dagger. The monsters rush toward her, infuriated, but are diverted by the discovery of Raglan dragging the Goddess through an opening in the roof. Confusion reigns. Tarzan, the Martling Party and D'Arnot battle their way out into the Lost City, where George rescues them with a machine gun he has concealed in a mysterious black case.

However, Raglan escapes through the underground passage, dropping the document as he flees. Martling, espying the document, gives it to Tarzan for safe-keeping.

Meanwhile, government officials, Ubico and Alvarez, learning that a ship carrying a contraband cargo of ammunition and firearms is bound for the Guatemalan Coast, commission Operator 17 to run down the smugglers.

Outside the passage, Raglan discovers his loss and knowing the Goddess is useless to him without the document, caches the Goddess and starts back, unaware that Ula Vale is watching him. 

Martling and his party start through the passage, hoping to overtake Raglan, but as George trips over a string a terrific explosion occurs. 

Plunged into darkness and half-buried in rocks and dirt the Martling Party realize that Raglan has laid this trap for them. Tarzan is missing, evidently having fallen through a large hole in the floor of the cave, from which can be heard the rush of a subterranean river.

Raglan hears the explosion and, with the aid of his two henchmen, digs his way to the party. Abashed to find the Goddess, telling them of his innocence and Martling invites him to join the search for the Goddess, telling him however, that the document has disappeared with Tarzan. 

Ula and her aides -- Garcia and Lopez, with the Goddess in their possession, approach the river's edge. Ula, arrested by Tarzan's unconscious form floating on the water, rescues him from a crocodile and is trying to revive him, when she sees Raglan approaching. She escapes with the Goddess, leaving Tarzan still unconscious. Raglan is about to search Tarzan for the document, when the Martling Party arrive and Tarzan regains consciousness. Nkima, the ape, tells Tarzan that he has been rescued by a woman who has fled with the Goddess.

After placing D'Arnot, Alice and Gordon on a mail boat bound for Puerto Barrios, Tarzan and the others start on Ula's trail. In the lead, Tarzan leaps into a native noose trap, set by Garcia, and with terrific force is whipped high into the air feet first. 

As Garcia lowers the apparently unconscious Ape-Man to the ground, Tarzan throttles him. Raglan, watching from the trail, decides to aid Garcia, and thus recover the document, but Tarzan drops Garcia to the ground, unconscious, freeing himself from the trap.

Garcia, refusing to betray Ula, warns her of danger with a signal.

After making camp, Raglan orders his two men to guard Garcia, while he joins the others in searching the river banks for a trace of Ula's kayuka. Martling and George take one kayuka -- Tarzan another. However Raglan returns to camp, where unable to bribe Garcia with money, he leaves a knife in reach of the man and hides in ambush, with his cohorts, awaiting Garcia's departure so that he can follow him to the Goddess.

Meanwhile, in Puerto Barrios -- D'Arnot having disembarked for France -- Gordon attempts to send a telegram in code for Major Martling. This arouses the suspicions of the Secret Service and Gordon and Alice are sent to Guatemala City under guard. 

George and Martling venture up a lagoon. Leaving their boat, to search for tracks, they become bogged in quicksand and start sinking rapidly, immediately by alligators. 

Tarzan, hearing George's frantic screams, rapidly makes his way to the lagoon. Leaping onto a liana, he reaches down and pulls the two to safely.

Back at the camp, Garcia dashes up a trail. Nkima, seeing this, shrieks loudly. Raglan sends his two men -- Paco and Nahua -- to follow Garcia and returns to camp, determined to annihilate the ape before Tarzan learns of Garcia's escape. While his shot at Nkima goes astray, Tarzan, Martling and George, hearing it rush back to camp. Raglan attributes the shot to Garcia's escape, telling them that his men will pick up the trail.

Garcia reaches Ula's hide-out and, while Paco returns to inform Raglan, Nahua falls into a trap and is taken captive. 

As night falls, Martling, Tarzan, George and Raglan take shelter with an Indian family. Paco, joining them, tells them that he failed to find the trail and has lost Nahua. Drawing Raglan aside, Paco enlightens him and the two make their way to a huge boulder overshadowing the hut in which the party is sleeping. From the opposite direction, Ula and her men are heading for the boulder.

Hearing the sound of machetes, Tarzan starts up the hill to investigate, but unseen hands release the boulder -- sending it crashing downward -- directly toward the house.

Tarzan picks up a smaller boulder, throwing it directly in the path of the oncoming boulder, which veers slightly and crashes into a corner of the house, destroying their food. 

In the morning, Raglan volunteers to hunt for game. He and Paco, surreptitiously hasten to Ula's hide-out where they find Nahua alone. As they are unfettering Nahua, Ula arrives. Raglan tries to bargain with her for possession of the Goddess. She states she will talk business when the document is produced. 

Meanwhile, Alice and Gordon reach Guatemala City where, they are notified that they will be detained until a satisfactory translation of the code message is obtained. Gordon is placed in jail, while Alice is allowed her freedom on condition that she remain in the city.

Annoyed at Raglan's lengthy absence, Tarzan goes in search of game. He is returning with his catch, when Raglan and his men sight him. Raglan draws his gun, just as a huge tiger leaps from the brush toward Tarzan, who jumps aside only to land in a brutal tiger trap, the spikes of which close about him.