 Kit Li, a cop on the Hong Kong Police bomb squad, responds to a call at a local school, where a terrorist group led by an individual calling himself "The Doctor" has taken a school bus hostage.He soon discovers his wife and son are on board the explosives-rigged bus.Kit sends a subordinate to disarm the bomb, but matters are complicated due to the intricate setup of the bomb, which eventually explodes, killing everyone on the bus, including Kit's family.