A Princess of Mars is a science fantasy novel by American writer Edgar Rice Burroughs, the first of his Barsoom series. It was first serialized in the pulp magazine All-Story Magazine from February–July 1912. Full of swordplay and daring feats, the novel is considered a classic example of 20th-century pulp fiction. After ten years of happily-ever-after with his Princess, John and the nobles of the City of Helium find out that the caretaker and the assistant have tragically died at the same time, without training anybody else in the secrets of the Factory.