John Carter of Mars Volume 2. Warlord of Mars & Thuvia Maid of Mars John Carter of Mars, the Prince of Helium, returns in Edgar Rice Burroughs' famous series. In Warlord of Mars, Carter embarks on a relentless search for his wife, Dejah Thoris, and must pit his wits against the remaining Therns and the renegade black dator, Thurid of the First Born. In Thuvia, Maid of Mars, Cathoris, son of John Carter, embarks on a hair-raising adventure to save the beautiful Thuvia of Ptarth from treachery, mind manipulators and the green horde! The planet Mars itself, as always, plays a colourful and exotic role in these fantastical adventures.