Nick and Jacob use the time traveling hot tub to try to get back to the past after Lou gets shot, but they inadvertently end up ten years in the future, which they must alter if they want to save their present-day environment.
Nick and Jacob use the time traveling hot tub to try to get back to the past to learn who shot him and undo the damage, but they inadvertently end up ten years in the future. Jacob reasons the assassin came from the future, which they must alter if they want to save their present-day environment.