Name this classic movie please?

I think this movie was released in the 1940s. There is an American, who I believe is in France. He has a boat and is staying at some motel. He is later requested to help transport some people across some body of water for which he is compensated. There is a girl who is younger than him and he offers her money so she can go back home. Later somebody gets hurt while on the boat so he is pushed into using his medical skills to help the guy. The injured guys wife shows up who mind you is hot and confronts the American but she mollifies as she sees that her husbands condition is improving. etc etc.