The family dog, Max, is kidnapped by Sirus Caldwell (Zack Ward) to be used as a product test subject. Max escapes but the new super energy drink he had been testing turns him into Monster Mutt (Bob Gibson). The Taylor family children, Ashley (Rhiannon Leigh Wryn) and Zach (Billy Unger) join up with the scientist responsible for his transformation, Dr. Victor Lloyd (Brian Stepanek), to find a cure and return Max to normal.