The Land That Time Forgot is a fantasy novel by American writer Edgar Rice Burroughs, the first of his Caspak trilogy. His working title for the story was "The Lost U-Boat." The sequence was first published in Blue Book Magazine as a three-part serial in the issues for September, October and November 1918. The complete trilogy was later combined for publication in book form under the title of the first part by A. C. McClurg in June 1924. Beginning with the Ace Books editions of the 1960s, the three segments have usually been issued as separate short novels.
Starting out as a harrowing wartime sea adventure, Burroughs’s story ultimately develops into a lost world story reminiscent of such novels as Sir Arthur Conan Doyle’s The Lost World (1912) and Jules Verne’s The Mysterious Island (1874) and Journey to the Center of the Earth (1864). Burroughs adds his own twist by postulating a unique biological system for his lost world, in which the slow progress of evolution in the world outside is recapitulated as a matter of individual metamorphosis. This system is only hinted at in The Land That Time Forgot; presented as a mystery whose explication is gradually worked out over the course of the next two novels, it forms a thematic element serving to unite three otherwise rather loosely linked stories.
The novel is set in World War I and opens with a framing story in which a manuscript relating the main story is recovered from a thermos off the coast of Greenland. It purports to be the narrative of Bowen J. Tyler, an American passenger sunk in the English Channel by a German U-boat, U-33, in 1916. He and a woman named Lys La Rue are rescued by a British tugboat. The tug is also sunk, but its crew manages to capture the submarine when it surfaces. Unfortunately, all other British craft continue to regard the sub as an enemy, and they are unable to bring it to port. Sabotage to the navigation equipment sends the U-33 astray into the South Pacific. The imprisoned German crew retakes the sub and begins a raiding cruise, only to be overcome again by the British. A saboteur continues to guide the sub off course, and by the time he is found out it is in Antarctic waters.
The U-33 is now low on fuel, with its provisions poisoned by the saboteur Benson. A large island ringed by cliffs is encountered, and identified as Caprona, a land mass first reported by the fictitious Italian explorer Caproni in 1721 whose location was subsequently lost. A freshwater current guides the sub to a stream issuing from a subterranean passage, which is entered on the hope of replenishing the water supply. The U-boat surfaces into a tropical river teeming with primitive creatures extinct elsewhere; attacked, it submerges again and travels upstream in search of a safe harbor. It enters a thermal inland sea, essentially a huge crater lake, whose heat sustains Caprona’s tropical climate. As the sub travels north along the island’s waterways the climate moderates and wildlife undergoes an apparent evolutionary progression.