Bullet Train

Code name, Ladybug, is a hitman who's had difficult times and is working with a therapist to reduce stress in his life and to be more positive. He's actively trying to be less violent. He's given an assignment to steal a briefcase from a moving bullet train. Unfortunately for Ladybug, the case is in the possession of other hitmen. Oh, and there are also several other dangerous people and 1 snake aboard the train. As the journey progresses, the briefcase changes hands several times and the reason so many violent people are on the train becomes apparent. The plot is carried on by the device of sudden cuts to earlier events to explain how the current situation develops.