David Innes and a versatile inventor named Perry had traveled downward into the earth in powerful machine called a subterranean prospector that could bore through solid rock. They discovered a strange world called Pellucidar at the core of the earth. It was inhabited by a primitive race of men who were terrorized and enslaved by superior race of lizard-like monsters called Mahars and a gorilla-like race called Sagoths, whom the Mahars used to capture their human slaves. David trained the human race to fight, and the Mahars and Sagoths were defeated in a significant battle. The tribes organized themselves into a federation, and they chose David to be their emperor.
David then returned to the surface to obtain supplies. He had married a girl called Dian the Beautiful and planned to take her with him, but his rival Hooja tricked him into taking a captive Mahar with him instead of Dian. For this reason, David returned to the subterranean world as soon as he had procured books, ammunition, and other necessary items.
David felt sorry for the Mahar whom he had accidentally brought to the earth’s surface, so he took her back to Pellucidar. He allowed the Mahar to escape.
When he reached Pellucidar, he found himself in unfamiliar territory and did not know how to find his friends. He wanted to reach a place called Sari, where his friend Ghak the Hairy was king. It was here that he hoped to find Dian.
By himself, he could not transport all the supplies that he brought from the upper world. He had to orient himself so that he could lead a party back to the subterranean prospector. This was difficult, since there were no stars, and the subterranean sun remained immovable directly overhead.
Fortunately, David had brought a compass and three pedometers from the upper world.
With the help of these instruments, he charted his movements and made an accurate map.
For a long, long time, David did not encounter any men. Then he saw his friend Perry, who was being chased by a group of gorilla-like Sagoths. He had brought plenty of ammunition with him, so he easily killed most of the Sagoths and scared the rest away.
Perry told David what had happened during his trip to the upper world. Hooja told a lot of lies. He told Dian that David had left her behind on purpose. He also told everyone that David was tired of living in Pellucidar and was never going to return. After a few days, Dian disappeared. Still later, Hooja also disappeared.
Hooja’s lies caused the friends of David to fight one another. Dacor the Strong One, the king of the Amozites and the brother of Dian, believed Hooja. Ghak the Hairy, the king of the Sarians, firmly believed that David had not betrayed them. Some of the other tribes of the federation sided with Dacor, others favored Ghak, and still others went off on their own.
The Mahars and Sagoths took advantage of the confusion and began to wreak terrible revenge upon the human tribes for the defeat that they had suffered.
Perry went to Amoz to look for Dian and to convince Dacor that David had not betrayed them. Dacor refused to believe him, and Dian was not at Amoz. A friend of Hooja came to Amoz and stirred up the people, so that Perry had to flee for his life. He then had his unfortunate encounter with the Sagoths.
David and Perry eventually came to familiar territory. They still did not know how to reach Sari, but David knew where the island of Anoroc was located. Ja of Mezop lived there, and Ja would be able to tell him how to reach Sari.
They had trouble reaching Anoroc. They had to cross cold mountains infested with huge bear-like creatures. Then they had to build a clumsy ship, and fight a battle with some of Ja’s enemies.
When they reached Anoroc, Ja gave them the desired information. It was decided that a party of Mezopians would take Perry to the subterranean prospector and fetch the supplies that David had brought. Meanwhile, David would return to Sari with some Mezopian guides, so that he could attempt to reestablish the confederacy.
While David and two Mezopians were traveling toward Sari, Sagoths killed the guides and captured David while the party was sleeping. They took David to Phutra, one of the cities of the Mahar. Here David was condemned to fight a monster called a tarag in an arena. If he survived, his life would be spared.
A girl was also condemned to face the tarag. She was armed with a javelin, while David had his revolvers. To David’s surprise, the girl was Dian.
While they were battling the tarag, three monsters called thipdars, who served as guardians for the Mahar queen, swooped down on the tarag and carried it away. The Mahars explained that they had interrupted the fight because Tu-al-sa had interceded for him. She was the Mahar whom David had inadvertently taken to the upper world. Because David had returned her to Pellucidar and set her free instead of killing her, she was grateful to him.
However, the Mahars refused to set David and Dian free unless David returned a secret formula that he had stolen during his first visit to Pellucidar. There were no male Mahars, but only females. In order to propagate, they needed the formula that David had stolen. Without it, the Mahar race would eventually die out.
David did not want to return the formula, since he felt that the human race would again be at the mercy of the Mahars if they could propagate. However, Dian pointed out that the Mahars would not be a threat to the human race if David was set free. With the technology that he had brought back from the upper world, the human race could easily deal with the Mahars. Moreover, if David did not return to reunite the splintered federation, the Mahars would continue to take advantage of their disunity, and the results would be catastrophic.
David agreed to return the formula. With a party of Sagoths, he went to the cave where he had hidden it. Dian had to stay in Phutra as hostage.
To his dismay, someone had taken the formula from the cave. When he returned to Phutra, he learned that Hooja had found the formula and returned it to the Mahars. The Mahars then allowed Hooja to take Dian with him. The Mahars granted David his freedom, but warned him never to come near any Mahar city again.
David went to Sari. Ghak was happy to see him, and the people were jubilant when they realized that their emperor had returned. They decided to look for Dian and rebuild their federation. For this purpose, they sent a delegation of twenty warriors to the ten major tribes. They wanted David to remain in Sari.
While David was fretting because of his enforced inactivity, Kolk came to Sari, accompanied by Thurian warriors. Kolk was the son of Goork, king of the Thurians. They had heard about the federation and wanted to join for two reasons. They wanted protection against the Mahars, and they were troubled by a band of renegades led by Hooja. This band even included some Sagoths, whom the Mahars had sent to help the wicked leader.
After receiving directions from Kolk, David set out for Thuria, hoping to rescue Dian. Kolk gave David a piece of bone. A picture of a beast of burden called a lidi was scratched on it. Underneath the lidi were a man and a flower. This piece of bone would serve as a letter of introduction to Kolk’s father.
On the way, he saved the life of a hyaenodon, which was called a jalok in Pellucidar. The hyaenodon returned the compliment by coming to David’s assistance when some of Hooja’s men attacked him. David tamed the hyaenodon, and called him Raja, but it left him after they reached Thuria.
One of Hooja’s men had stolen David’s possessions, including his firearms and the piece of bone that Kolk had given him As a result, Goork did not trust him, so David had to go alone to the island on which the stronghold of Hooja was located.
When he reached the island, he was captured by a race of gorilla men who were hostile to Hooja. Gr-gr-gr, their chief, thought that David was one of Hooja’s men and planned to kill him. Then an army of Hooja’s men attacked the gorilla-men. With David’s strategic help, the invaders were slaughtered and driven away. Gr-gr-gr became his friend and set him free. [These creatures were not Sagoths, but a different race.]
While attempting to penetrate the stronghold of Hooja, he met Juag, who explained that Hooja had captured his village and taken him prisoner. Juag was the king’s son, and Hooja tried to cultivate his friendship. He was planning to fight a major war and hoped that Juag would persuade his father’s warriors to return to the village and join his expedition.
Since Dacor the Strong, the brother of Dian, had once saved the life of Juag, Juag used his influence with Hooja to protect Dian from Hooja’s lascivious attentions. But now, because Juag was involved in a plot against Hooja, Juag was making a desperate attempt to escape. He was about to fetch Dian and leave the island in a boat. Instead, David fetched Dian while Juag went to the boat and waited for them.
As they were about to escape, they had to fight Hooja’s men. During the struggle, the boat was destroyed. So they went to the other side of the island where David had hidden the boat in which he had come to the island. They were briefly captured by Hooja’s men before they got away, but Gr-gr-gr and his warriors rescued them.
Sari lay on the other side of the ocean from Thuria, so David decided to put a sail on his boat and cross the ocean. He would rely on his compass to find his way across.
Since they journey would take a long time, they first had to return to the mainland and hunt for food. During the hunt, Raja reappeared with his mate. David called her Ranee.
When they had enough to eat, Dian, David, Juag, and the two hyaenodons boarded the boat and attempted to cross the ocean. As they approached their destination, a storm blew them out to sea. They lost their compass and could not find land.
Hooja’s warlike expedition had also been blown out to sea. When they saw David’s boat, they chased it. Since David had equipped it with a sail, it temporarily escaped the enemy. However, when Hooja spotted them the second time, their sail broke, and they were in danger of being captured.
In the meantime, Perry had been busy building warships with canons. They appeared on the scene and defeated Hooja’s men in a naval battle. Hooja died.
The federation had also been pieced together, and the sailors were glad to see their emperor.
The fleet sailed to Hooja’s island and captured the village. Juag became king, and amicable relations were established between his people and the gorilla-men.
Starting with Phutra, David and his Imperial Navy attacked and destroyed the Mahar cities one by one. Some of the Sagoths were captured. They readily agreed to change masters and serve the federation instead of the Mahars.
David and Perry then taught the inhabitants of Pellucidar peaceful pursuits, such as farming. They also taught them how to use wireless and telephones. One intelligent young man even learned how to read.
David built a well ventilated house for Dian and himself. Other inhabitants of Pellucidar followed their example, but many preferred their old cave dwellings.
David was universally honored as emperor. However, his chief delight was the presence of his loving empress, Dian the Beautiful.
To write this summary, I consulted an online version of Burroughs’ novel presented by Project Gutenberg.
Project Gutenberg: Pellucidar by Edgar Rice Burroughs