'1914. Knight poses as rating aboard son's cruiser and helps Q-ship sink U-boat.' (British Film Catalogue)

Young heiress Margaret Yeoland is found unconscious on the Devonshire moors by a disillusioned author, Denis Marlowe. She tells him she has run away from her family, but is reluctant to reveal the full story. Intent on concealing her identity from her pursuers, Denis coerces her into marrying him. But when the body of Margaret's missing father is discovered, it leads Denis to suspect his wife of murder.