Thuvia, Maid of Mars

Burrough's fourth Barsoom novel, Thuvia, Maid of Mars introduces us to a new prince of Helium. Carthoris, son of John Carter of Mars and Dejah Thoris, is hopelessly in love with Thuvia, princess of Ptarth. She's already pledged to another, and on Barsoom, engagements can be broken only by death. Though honor dictates that Carthoris can't kill his rival, that's the least of his worries. Thuvia suddenly vanishes, and Carthoris finds himself up on kidnapping charges. He must rescue to save Thuvia, clear his name, and prevent an inter-kingdom war. Carthoris's sabotaged flier goes down in an unexplored region of Barsoom. Carthoris is forced to travel through ancient ruins to find Thuvia, kidnapped by yet another rival prince. Then Carthoris and Thuvia must escape the Torquas. They're helped by the Lotharians. But the enemy of thy enemy isn't always a friend. Carthoris and Thuvia will have to tread carefully among these treacherous new allies.