Capri Cavalli is an average university student whose world goes awry when her brother Steve Cavalli and his friend David Kazan are killed by some bullies led by Arnold Rothsfield. As Capri tracks down Arnold, she learns that the threats are linked to the Shaw crime family. She goes after the clan to take revenge, but they brutally suppress her, cutting off her left hand. Capri escapes and seeks shelter with David's parents, Ross Kazan and Elizabeth Kazan, two kind-hearted mechanics, who fit him with a multi-barrel machine gun prosthetic. Capri and Elizabeth (who uses a chainsaw) follow the clan, massacre them one by one. Meanwhile, the families of their victims unite to seek revenge.
Finally, they reach the gang's hideout. As the fighting continues, Elizabeth loses her right leg and eventually dies. Capri loses her machine gun during a fight with Arnold Rothsfield's father, Andy Rothsfield, but finds Elizabeth's chainsaw. While finding Arnold with hostages to keep Capri at bay, his mother Monica manages to disarm Capri while attempting to kill him with her drill bra. Seeing one of the hostages wet himself, Capri takes advantage and makes Monica go on the pee, giving her an electric shock. She then kills Arnold. Realizing that she has nothing left to live for, she attempts to commit suicide. At the same time, Capri hears a noise behind her and turns, sword ready.
