On the night of 1 August 1914, Commander Corlaix of the French Navy and his wife, Yvonne, arrange a shipboard dinner for the officers of his cruiser.  Afterward, Lieutenant D'Artelle asks Yvonne to stay on board with him, and when Corlaix (learning by classified wireless that war has been declared) abruptly orders her from the ship, she goes instead with D'Artelle to his cabin.

The ship is sunk by a torpedo, and Corlaix is brought up before the Admiralty Court on charges of incompetence.  Yvonne comes forward to testify and, by compromising herself, proves her husband's adherence to duty.

Corlaix, realizing Yvonne's great love for him, forgives her for her indiscretions, and they are reunited.