Set in the fictional town of Keening, Massachusetts, the movie follows Karen O'Hara (Courtney Halverson), a young woman who is largely unaware of the town's true bloody past. About sixty-six years ago, a horrific massacre devastated the town, and since that time the town has decided to forgo any St. Patrick's Day festivities. The town managed to temporarily rid themselves of the killer, a bloodthirsty leprechaun, by sending it to another dimension by way of an old book. However, Karen accidentally sets the monster free one day while she is out hunting. The leprechaun immediately sets about killing several people, but Karen's father, Sheriff Conor O'Hara (Billy Zane), is unwilling to believe Pop O'Hara's (William Devane) claims that the murders are perpetuated by a supposedly mythical being.