The book's plot is divided into two roughly equal parts, the first dealing with Teichmann's career on a minesweeper and the second with his service aboard a U-boat.

In both branches of naval service, the Germans first manage to hold their own but the Allies increasingly get the upper hand, and in both cases Teichmann's involvement ends with a traumatic shipwreck and the horrors which scavenging gulls can inflict on helpless sailors adrift on the sea.

Teichmann feels no hatred or animosity towards the British sailors opposing him, regarding them as fellow mariners who due to circumstances were thrust into the situation of trying to kill him.

This episode ends much more brutally than in The Caine Mutiny - crew members cut the captain's throat while he lies drunk, and throw his body overboard to be chewed up by the ship's propeller and hide the manner of his death.

In the U-Boat Teichmann serves under a completely different kind of Captain - harsh and tyrannical, but highly courageous and an incomparable skillful seaman, so that even while hating him the crew are willing to trust him with their lives.

In a postscript, it is noted that the gulls have drawn the attention of a German patrol boat, which arrived to find seven of the U-boat survivors still alive.