Homicide detective John Hobbes witnesses the execution of serial killer Edgar Reese. Soon after the execution the killings start again, and they are very similar to Reese's style.

In the year 2035, convict James Cole reluctantly volunteers to be sent back in time to discover the origin of a deadly virus that wiped out nearly all of the earth's population and forced the survivors into underground communities. But when Cole is mistakenly sent to 1990 instead of 1996, he's arrested and locked up in a mental hospital. There he meets psychiatrist Dr. Kathryn Railly, and patient Jeffrey Goines, the son of a famous virus expert, who may hold the key to the mysterious rogue group, the Army of the 12 Monkeys, thought to be responsible for unleashing the killer disease.

Ed Lover and Doctor Dre are two inept barbers. Deciding that maybe they ought to find another line of work, they join the police. A big mistake, as far as their duty sergeant, Sgt Cooper is concerned, who proceeds to harass them at every turn. Despite this, they discover a major crime, and proceed to solve it in their own unusual fashion.

A sheltered Amish child is the sole witness of a brutal murder in a restroom at a Philadelphia train station, and he must be protected. The assignment falls to a taciturn detective who goes undercover in a Pennsylvania Dutch community. On the farm, he slowly assimilates despite his urban grit, and forges a romantic bond with the child's beautiful mother.