This comic Joe Dante effort is set in a Norman Rockwell-esque small town at Christmastime. Seeking a unique gift for his son an erstwhile inventor (Hoyt Axton) purchases a cute, fuzzy little "Mogwai" from a Chinatown shopkeeper's (Keye Luke) grandson (John Louie), who dispenses the above-mentioned warning before closing the deal.

Meanwhile, young bank clerk Billy Peltzer (Zach Galligan) must suffer such antagonists as rich-bitch Mrs. Deagle (Polly Holliday) and priggish Gerald (Judge Reinhold) while pursuing his romance with Kate (Phoebe Cates). These and a variety of other plot strands are tied together when the lovable mogwai (named Gizmo) is exposed to bright light and gotten wet.

In short order, the town is invaded by nasty, predatory Gremlins, who lay waste to everything in sight as Billy and Kate try to contain the destruction. Like most of Joe Dante's works, Gremlins is chock-full of significant cameo appearances: in this instance, such pop-culture icons as Dick Miller, Jackie Joseph, Chuck Jones, Scott Brady, Harry Carey Jr., Steven Spielberg (the film's executive producer) and even Robby the Robot all show up briefly on screen.