The first book in his Caspak trilogy, The Land That Time Forgot, is a fantasy book by American author Edgar Rice Burroughs. The first chapter of the book, which takes place during World War I, is framed by the discovery of a manuscript recounting the plot from a thermos off the shore of Greenland. It claims to be the story of Bowen J. Tyler, an American passenger who was sunk by the German U-boat U-33 in the English Channel in 1916. By the time the saboteur is discovered, the submarine has already entered the Antarctic seas after being led off course. A group of beast men assault the castaways and capture Ahm, a Neanderthal Man. They discover that the island's indigenous name is Caspak. They find oil, which they intend to convert into U-33 fuel. Tyler departs from the other survivors to find Lys and save her. The many bands of near-human primitives, each of which represents a distinct stage of human development, engage in a series of adventures.