The night that wealthy Mrs Chan gives birth to identical twins, all hell breaks loose in the hospital! A wounded gangster escapes from a police escort in the emergency room and snatches one of the twins as hostage.

The distraught parents lavish all their love and affection on the remaining twin throughout his childhood. He studies music and becomes a world-famous conductor. The abducted baby is abandoned by the gangster and found by a dance hall hostess who takes the infant home and brings him up as best she can. His youth is spent in the company of thieves and gangsters but he manages to get a job as a mechanic.

Years later when the two Chans, by coincidence, meet face to face - chaos reigns. There is no time to establish a relationship but they both run headlong into great danger and a series of mind blowing stunts, that only Jackie Chan & Jackie Chan can deliver.