British comedy starring Jack Buchanan and Greta Gynt. After battleship Captain Mailtand (Buchanan) enjoys a large party in honour of his next voyage, he finds two young women (Gynt and Kay Walsh) still aboard the ship once it has set off. To protect the trespassers as well as himself, he agrees to hide them in his quarters but it proves difficult to keep them concealed with the Admiral (Fred Emney) unexpectedly onboard, resulting in hilarious consequences.

In World War One, Martha Cnockhaert (Madeleine Carroll) works as a spy in a German hospital, acting for the allies. Aided by orderly Stephan (Herbert Marshall), Martha plots to blow up a German ammunition dump. When Martha accompanies a German Commandant to Brussels, a change in the Kaiser's movements inadvertently reveals Martha's true purpose.