When Billy Peltzer (Zach Galligan) is given a small creature called a Mogwai by his father Randall (Hoyt Axton), he is unaware of the carnage he is about to encounter. There is a huge responsibility in looking after Gizmo as there are certain rules which must be followed. The Mogwai must be kept away from bright light, never made wet and never, ever be fed after midnight. When an accident occurs involving Gizmo and water, the next evolution stage of the Mogwai appears, and it isn't nice at all.

With its bouncy, devil-may-care attitude, the Gremlins Rag is one of Goldsmith’s most enduring character themes, but when you actually examine the score in detail, it’s interesting to note how often Goldsmith uses it as a little heraldic leitmotif, hinting at the impending appearance of the nasty little gremlins. The Rag is offset by a truly beautiful, lyrical theme for Gizmo, which also doubles as a romantic theme for the young lovers in the film, Billy and Kate. Gentle, tender, and usually performed on synths doubled with high-register strings and mysterious echoing bell effects.