Catherine, Emilie Ullerup and Francois, Adam Boys, are fleeing a looming menace when the attacker closes in, dragging Francois to a grim death. The same creature seizes Catherine just as she reaches a grassland monolith.
Four American college friends, Sophie, Stephanie Bennett, Ben, Andrew Dunbar, Jeni, Melissa Roxburgh, and David, Brendan Fletcher, are vacationing in the Irish countryside at Sophie's suggestion. Ian, Bruce Blain, their driver, drops them near the monolith seen in the opening. Sophie, a history major, notes the symbol carved on it before heading to a local bar with the others, where they meet a friendly old man, Hamish, Garry Chalk, who tells them the village’s history: it used to be a mining center for gold in a nearby cavern, but when the gold ran out, the population dwindled. The four agree to be driven to a cottage to begin hitchhiking toward the cavern, though they are wary of Hamish and his grumpy son, Sean, Teach Grant.
That night, Jeni investigates a ruckus outside and glimpses a figure sprinting past the window. She wakes the others, who discover that Hamish and Sean have locked them up. A figure enters the cottage through the fireplace and forcibly takes Jeni’s gold earring. After a brief struggle which sees David’s leg bitten by the monster, the four escape the cottage and race to the village hall, where they hide in the cellar. Sophie learns from a mythology book that the monster is a Tuatha Dé Danann, also known as a leprechaun, who owns the gold that the villagers sought after. The leprechaun lusts after gold, but it can be repelled by a certain symbol, the same one carved into the monolith, which serves as a barrier beyond which the being cannot get out. There was another monolith symbol barrier at the leprechaun’s cave; however, when the villagers mined the cave and took the gold, the cave collapsed, causing the leprechaun to escape 15 years ago. Hamish and Sean join Ian outside, where Hamish tells him of his suspicions that his son is growing disillusioned with their sacrifice scheme.
The four are confronted by Hamish, who confirms that the villagers sacrifice tourists each year to avoid having to sacrifice themselves, and Sean, who has grown weary of the unjustified sacrifices, eventually lets them go, while Hamish finds Ian impaled on some farm equipment in a shed. He escapes as the creature kills Ian. The four are then aided by Mary, an old woman revealed to be Hamish’s accomplice, who offers them a chance to flee. They are tied to trees as offerings for the leprechaun. The monster arrives and rips out Jeni’s golden tongue ring. David manages to keep the leprechaun away from Jeni, but the beast slashes his torso, also cutting the rope, allowing him to break free and free the other three before he is attacked and killed. The remaining trio return to the cottage to set a trap to kill the monster, but the leprechaun tricks Sophie and Ben into striking Jeni with their axes, killing her.
Sophie and Ben fetch Hamish’s truck but are cornered by the leprechaun inside the village hall. The leprechaun eventually grabs Ben and kills him by ripping his spine out. Though cornered by Hamish, who remains intent on sacrificing her, Sophie is saved by Sean, who pushes Hamish into the cellar out of guilt for the long history of sacrifices. The leprechaun kills Hamish in the cellar, much to Sean’s devastation. Meanwhile, Sophie boards Hamish’s truck but crashes midway while trying to avoid the leprechaun. She resumes her escape on foot, and when the leprechaun finds her, she distracts it with gold coins, then kills it using Francois’s knife, which he had left in the prologue. Sophie finally manages to cross the monolith to safety just as three leprechauns are revealed running in the tall grass before continuing her escape.
