Daniel (Ralph Macchio) moves to Southern California with his mother, Lucille (Randee Heller), but quickly finds himself the target of a group of bullies who study karate at the Cobra Kai dojo. Fortunately, Daniel befriends Mr. Miyagi (Noriyuki “Pat” Morita), an unassuming repairman who just happens to be a martial arts master himself. Miyagi takes Daniel under his wing, training him in a more compassionate form of karate and preparing him to compete against the brutal Cobra Kai.
Teen misfits Gary (Anthony Michael Hall) and Wyatt (Ilan Mitchell-Smith) design their ideal woman on a computer, and a freak electrical accident brings her to life in the form of the lovely, superhuman Lisa (Kelly LeBrock). She outfits Gary and Wyatt in cool clothes, surprises them with a Porsche and helps them stand up to jerks Ian (Robert Downey Jr.) and Max (Robert Rusler). But, all the while, the boys must hide Lisa’s existence from Chet (Bill Paxton), Wyatt’s nightmare of a big brother.