Think Fast, Mr. Moto (1937)
Mr. Moto is a Japanese detective on a ship to Shanghai who notes some sinister business. As he investigates, he turns up some shady dealings.
Highlight to read the spoiler:
Moto is pretty cavalier about the law. He casually dumps this guy overboard because he’s up to no good. I was shocked that he just outright kills him.
I didn’t expect most of the events in the movie. I am not recommending it but it is a curiosity on a lot of levels.