Nightmare on the Dark Night Express

Two passengers and a train conductor unexpectedly discovered that someone had died in the carriage of the night train. They further found out that the guy was carrying valuable diamonds. In order to keep those diamonds, they decided to create a false impression that this person never got on the train. Therefore, they conspired to throw the body into the river along the way. The conspiracy of disposing the body gradually escalated into where to dismember the person so that the body could fit into a small suitcase. Later, they became more and more疯狂, seemingly bringing out each other's beastly nature.