The taciturn, stubborn, autocratic, violent Police Detective John Kimble (Arnold Schwarzenegger) has pursued drug dealer Cullen Crisp (Richard Tyson) for years. He finally arrests Crisp for murder, but is unable to convict him due to the refusal of a witness named Cindy (whose boyfriend Danny was shot and killed by Crisp) to identify the killer. After Kimble psychologically humbles Cindy, Crisp is identified in a police line-up. Kimble, accompanied by Detective Phoebe O'Hara (Pamela Reed), is then ordered to go undercover in Astoria, Oregon, to find Crisp's ex-wife Rachel and their son, who are hiding from him, and offer her a deal to testify against Cullen. Since their appearance is not known to them, O'Hara is to act as the substitute teacher of the son's kindergarten class at Astoria Elementary School while Kimble has to track down the identity of the mother, who is believed to have stolen money from Crisp.