House on the Waterfront

Captain Le Quévic intends to raise a sunken ship at the entrance to the port of Marseilles, not knowing that it contains the body of a murdered woman. The ship’s owner, a local gangster named Black, plans to sabotage the operation, since he was the man who killed the woman to prevent her from revealing his crooked activities. To that end, he bribes Le Quévic’s young diver, Michel, to blow up the wreck with explosives. When he discovers the truth, Michel decides to flee with the dead woman’s sister, Martine, with whom he has fallen in love. Angered by this betrayal, Black captures Martine, so that he can coerce Michel into carrying out his orders… —Filmsdefrance.com