NIGHT TRAIN

Two passengers (Sobieski and Zahn) and the conductor (Glover) discover that a person has died in their night train cabin after taking an overdose. They come across "valuable jewels" in a small box which the man had brought with him and decide to keep it for themselves.
To make it look as though the man never boarded the train, they conspire to dump his remains in a river that the train passes by. Their scheme to get rid of the corpse escalates to a point where they have to chop up the body just to fit it into a small trunk. This is only the beginning of a series of intricate plot-twists, mainly revolving around the changing desires of each person on board the train. Eventually it is revealed that the box is apparently supernatural, and that whoever looks into it sees only what would tempt them the most, dooming them to corruption and death before dawn. The conductor, Miles, ultimately survives long enough to attempt to destroy the device by placing it in the path of an oncoming train. He dies just after seeing it nudged off the tracks by a curious dog.