War drama starring Tyrone Power as Lt. Ward Stewart (Tyrone Power) who, after serving with distinction as the commander of a PT boat, is given a new and more challenging assignment aboard a submarine by his uncle, Adm. Bob Stewart (Minor Watson). Before shipping out, Ward spends the night with a pretty schoolteacher, Jean Hewlett (Anne Baxter). However, when Ward reports for duty, he discovers he'll be serving under Lt. Cmdr. Dewey Connors (Dana Andrews), who happens to be Jean's boyfriend. On leave and on land, Ward and Dewey are soon caught up in a romantic rivalry, while on duty and under the water they must work together to ferret out Nazi U-boats.