The story begins were the last book left off. John Carter finds out that the black pirate Thurid knows how to enter the chamber his wife is imprisoned in. He tracks him down and comes upon him and the leader of the Therns Matai Shang. They have freed the three women. Carter is too late to save them and gives chase.
The trail ends at the north pole. Finding an entrance to the impassable barrier that surrounds the pole, Carter discovers the lost race of yellow men. He saves a yellow warrior who he finds out later is a rebel prince. With his help Carter disguises himself and enters the capital city. There he finds many red men captives including his father and grandfather in-law. The yellow men have harnessed the magnetic pole and crash ships that cross the barrier.
Carter leads a revolt and destroys the giant magnet allowing his allies to cross the barrier. It all leads to a final confrontation that reunites him with his wife and being proclaimed the Warlord of Barsoom.
The third book in the series continues seamlessly where Gods of Mars left off. It is filled with non stop action and adventure. I think the first three books in the Martian series is the best that Burroughs ever wrote.