Willis plays Art Jeffries, an undercover FBI agent who protects a nine-year-old autistic boy, Simon Lynch (played by Miko Hughes), who is targeted by government assassins after he cracks a top secret government code.
a nine-year-old autistic savant named Simon Lynch is given a sophisticated puzzle book by his teacher. Simon quickly solves a particular puzzle and phones a number encoded in the solution. This call reaches two National Security Agency cryptographers,
their boss, Lieutenant Colonel Nick Kudrow, who severely rebukes the pair for their unauthorized actions, describing Simon and his abilities as a national security threat. Two assassins, Peter Burrell and Shayes, are sent by Kudrow to terminate the boy and his parents, Martin and Jenny.