The Land of Time Forgot - Edgar Rice Burroughs

PLOT SUMMARY
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.