Who's that girl waving a semaphore message of 'I Love You' to a destroyer as it departs New York for World War I? It's Sally, the Coney Island saltwater-taffy girl. Each of the sailors, especially pals and romantic rivals Baltimore Clark, Dutch Herman and Skeet's O'Reilly, hopes the message is for him. But rivalries end where warfare begins. The pals are soon assigned to the crew of a merchant ship posing as a German communications boat. The mission: rendezvous with U-boat captains and learn their plan of attack. Bill Boyd, Robert Armstrong and James Gleason play the three friends. And who's that girl? It's captivating 20-year-old Ginger Rogers, two years before she and Fred Astaire would go Flying down to Rio.