After ten years of inexplicable exile on Earth, John Carter is returned to Mars. He finds what looks like a paradise, but it is actually hellish place ruled by the therns who act like gods. But even the gods have enemies, namely the race of black men called the First Born who terrorize the therns in turn at the behest of their death-goddess Issus. There's a lot of swordplay, narrow escapes, and the introduction of some new characters like the slave-girl Thuvia and the thern princess Phaidor, who of course fall in love with John Carter, but to his credit he remains loyal to his wife Dejah Thoris. We don't get to see much of Tars Tarkas or Sola in this story, but we do meet Carter's son, Carthoris (although it isn't clear exactly how old the kid is. Sometimes he's called "boy" and sometimes "young man" and he seems to know be an excellent warrior, but Carter has only been gone ten years, so do Martians just grow up faster or is Cathoris a really precocious ten-year-old? I have no idea.) Burroughs manages to keep Mars fresh by introducing us to new people and places on the dying planet, and leaves us on a cliff-hanger.