A 12-year-old Sam Pepper, lost her mother in a car accident, and her reclusive, quirky nature makes her an easy target for bullying. Realizing she'd had enough, Sam orders the parts to build a "Monster" from a comic book ad, and is finally able to get back at the bully. When Sam discovers her father Roy (Hopkins) proposed to his girlfriend Sydney (Carpenter), she relies on her monster to keep her from getting a new mom.