An unknown lethal virus wiped out five billion people in 1996. By 2035 only 1% of the population survive and they are forced to live underground. Convict James Cole reluctantly volunteers to be sent back in time to 1996 to gather information about the origin of the epidemic (which he's told was spread by a mysterious Army of Twelve Monkeys). Unfortunately Cole is mistakenly sent to 1990, six years earlier than expected, and is arrested and locked up in a mental institution, where he meets Dr. Kathryn Railly, a psychiatrist, and Jeffrey Goines, the insane son of a famous scientist and virus expert...