The story is narrated first-person, in the style of Burroughs' writing, by an unnamed man who has just returned to his
Virginia cabin after fishing, when he is confronted by Woola, the
Barsoomian calot (a
bulldog-like predator) of
John Carter, Warlord of Mars, who has appeared to relate his latest adventure to his nephew. The narration then assumes Carter's voice as he tells his story (from references he makes, it is set after
The Warlord of Mars and before
The Chessmen of Mars: he is already Warlord of Barsoom, but his only child is
Carthoris). Carter is at a party in
Lesser Helium, speaking with
Kantos Kan and
Mors Kajak when he realizes that
Dejah Thoris has gone missing. With Kantos Kan, he finds evidence that she has been kidnapped in a scuffle. Assuming that the kidnappers arrived in two fliers but only escaped in one, Kantos Kan and John Carter enter the other and, finding the coordinates already set, give pursuit. For half a (Martian) day they fly over an unrecognized portion of Barsoom, finally coming to rest above a complex built around a massive pit. There, they are captured by a band of
Red Martians and placed in a cell where a
Gathol army officer named Bas-ok, is already held. Bas-ok explains that they are held captive by the
sarmaks (a leathery-skinned, tentacled race) who have taken them captive in order to drink their blood. The cell is shaken by a massive explosion, which Bas-ok describes as that of the giant cannon in the center of the complex, launching cylindrical spacecraft against
Jasoom. Overpowering the guards, Carter and his companions escape, with him sending Kantos Kan to rally the forces of Helium and with himself and Bas-ok searching for Dejah Thoris. The narration again assumes Carter's nephew, who explains that he must wait to tell the rest of the story, but gives a brief overview in which Bas-ok betrayed Carter to the sarmaks and was killed for it; and John Carter, after a battle in the sarmaks' feeding chamber, rescued Dejah Thoris and destroyed the cylinder-launching cannon after the tenth blast (explaining why only ten cylinders landed on Earth in
The War of the Worlds), and finally led "the navy of Helium...the combined forces of the green men of
Thark and Warhoon, the black First Born, and red men from many cities and nations" against the sarmaks. The narration concludes with assurance of Carter's victory. ==Significance==