Kangran Song, a well-known bomb disposal expert, boards a train that has been planted with a timebomb. It appears to be a premeditated crime. Also on the train are famous cram school teacher Liu Kai, who has been caught having an affair, as well as Kangran’s mother. The timebomb is linked tothe speed of the train, and the countdown will accelerate if the train slows down. The timebomb cannot be defused, or it will trigger another bomb placed somewhere else in the city. This moral dilemma makes Kang-ran recall a similar tragedy from his past, in which he chose to detonate anotherbomb in order to save himself. What will he choose this time? Can he defuse the bomb and save everyone?