When a space capsule crash lands onto Susan Reynold's car she's doused by its alien liquid contents, Quantonium which turn her into a 48 foot 11 inch giant. Her wedding thwarted, she's captured by the military and sent to a secret government facility, where she meets fellow monsters Dr. Cockroach, Ph.D., the gelatinous BOB, The Missing Link, and Insectosaurus. Susan, aka Ginormica, is drafted to lead this motley crew of reluctant heroes to save the earth from the evil alien Gallaxhar, who's hell bent on retrieving his liquid Quantonium.