A British woman visits her husband at the Mexican mine he is attempting to reopen and discovers that the workers refuse to enter the mine, fearing an ancient curse. The couple enter the mine to prove there is no danger and inadvertently release a demon which possesses people's left hands and forces them to behave in a suitably diabolical manner.

Fashioning himself as a priestly avenger, Robert escapes from the insane asylum and begins slashing his way through anyone who stands between him avenging the actions of his greedy uncle.