Forty-three million miles from the earth--a succession of the weirdest and most astounding adventures in fiction. John Carter, American, finds himself on the planet Mars, battling for a beautiful woman, with the Green Men of Mars, terrible creatures fifteen feet high, mounted on horses like dragons.

Beginning with John Carter's return to Barsoom (Mars) after a ten year hiatus — separated from his wife Dejah Thoris, his unborn child, and the Red Martian people of the nation of Helium, whom he has adopted as his own — John Carter materializes in the one place on Barsoom from which nobody is allowed to depart: the Valley Dor, the Barsoomian heaven.

Old acquaintances, made in the two other stories, reappear: Tars Tarkas, Tardos Mors and others. There is a happy ending to the story in the union of the Warlord, the title conferred upon John Carter, with Dejah Thoris.

In this novel Burroughs focuses on another a younger member of the family established by John Carter and Dejah Thoris, protagonists of the first three books in the series. The heroine this time is their daughter Tara, princess of Helium, whose hand is sought by the gallant Gahan, Jed (prince) of Gathol. Both Helium and Gathol are prominent Barsoomian city states.