After a ten-year hiatus, John Carter returns to Mars and finds himself in the Valley Dor, a place no one is meant to leave. This is the Martian version of the afterlife. Here, Carter unearths a sophisticated plot masterminded by the Therns, who have used bogus religious promises to trick the other races of Barsoom for millennia. In addition to his ally Tars Tarkas, Carter makes new friends in the Thern princess Phaidor and the slave girl Thuvia. Together, they encounter many dangerous situations, such as fights with the fearsome Black Pirates of Barsoom.

The political and social complexity of Burroughs' Martian universe is further explored in this sequel to A Princess of Mars, which also presents the protagonist with new allies and foes as it explores themes of deceit, colonialism, and the pursuit of both individual and societal salvation. Though clearly science fiction, it is recognized for having had a significant impact on the planetary romance subgenre, fusing exotic locales, speculative science, and daring adventure. It differs from space operas in that it places more of an emphasis on surface locations than spacecraft.

This case laminate collector's edition includes a Victorian inspired dust-jacket.