chunk: Airedale Terrier Nobs on a ship sunk in the English Channel by a German U-boat, U-33, in 1916. He is rescued by a British tugboat with another survivor, Lys La Rue. 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 Atlantic. 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.