Charlie Chan at the Wax Museum

Charlie Chan at the Wax Museum is a 1940 mystery film starring Sidney Toler as detective Charlie Chan. Revisiting an old case results in fresh deaths.

Chan becomes certain that Butcher Dagan framed Rocke, his business partner, and that he killed Von Brom as well. Dagan was supposedly murdered by McBirney, another business partner and a friend of Rockes. With Cream having operated on Dagan, no one knows who among those gathered at the museum is him Jimmy even suspects Mrs. Rocke. Dagan kills McBirney and makes an attempt on Chans life, before the detective finally unmasks and captures him.

Source: Wikipedia