Pete Smith, a lift bridge operator in a harbor, feels lonely in his cabin, his only visitor being a policeman on patrol, Sgt. Coughlin. One night, after hearing shots, Smith gives shelter to a wounded man, whom he hides from Coughlin. Before leaving, the man, Marcas, promises to return the favor and the coat he borrows from him. Later, Smith enters the police, and his chief, Mather, suspects he is protecting Marcas, who is actually a gangster. Marcas sends a girl, Mary Monks, to deliver a luxuri...