American Howard Hallenbeck brings his family to rural Ireland for a vacation while he researches sites of religious significance. He is especially interested in sacred locations that predate Christianity, particularly those associated with Neolithic sites and fertility cults. Howard comes to the village of Rathmorne asking town priest, Reverend Coot, if he can photograph the graves and examine the parish records, believing the church was built on such a sacred site. Meanwhile, farmers use a tractor to remove a stone pillar in the middle of a field, but the pillar will not budge. When the other farmers leave, Tom Garron notices smoke erupting around the pillar foundation. A moment later, lighting strikes the pillar, which falls to the ground and Rawhead, a nine-foot tall beast with a demon’s face, emerges from the dirt. As this happens, Howard notices the eyes of a beast depicted in one of the church's stained glass windows glowing a bright red. The stained-glass beast resembles Rawhead. Later, Declan O’Brien, the church “verger” who helps with services and performs handyman duties, touches a chest on the altar. The heat from the chest scorches his hand, demonic images fill his mind, and the demon possesses him. Elsewhere, farmer Dennis Nicholson’s wife, Jenny, sends her husband outside to bolt the barn door. Dennis thought he had already latched the door, but discovers the bolt has been broken. Inside, Rawhead attacks Dennis, then goes to the house and attacks Jenny. However, when the demon notices she is pregnant, he does not kill her. When a villager finds Jenny Nicholson, she attacks him as if possessed, then backs down and screams in agony. Police take her away in an ambulance. Rawhead drags Dennis Nicholson’s body through the woods and ties him upside down from a tree branch and begins eating his remains. In a nearby trailer park, teenagers Andy Johnson and Katrina take a walk in the woods and discover Dennis Nicholson’s body. They run screaming, but Rawhead intercepts them and kills Andy. When Katrina returns to the trailer park, she tells the residents what happened. The villagers go into the woods and find the bodies of Dennis and Andy, but their heads have been removed. At the town pub where Howard Hallenbeck and his family rent rooms, Howard cannot sleep and takes a walk. He notices Rawhead standing on a nearby hilltop, but the creature quickly disappears. The next day, Howard reports that he saw something not human, but police dismiss him. Soon after, farmer Tom Garron’s body is discovered at the site of the stone pillar. Police now have three unexplained deaths to investigate. At the church, Rev. Coot cannot locate the parish records. Howard photographs the stained glass windows, but notices the demon’s eyes no longer glow. He sees the window inscription, which translates to, “Death goes in fear of what it cannot be.” Declan O’Brien finds Howard in the sanctuary, breaks his Polaroid camera, and chases him away. Howard and his family check out of the pub, pack their car, and leave town. A few miles outside the village, Howard’s toddler daughter, Minty, reports that she needs to urinate. Howard pulls to the side of the road, and he and his wife take the girl into the nearby field. As this happens, Rawhead emerges from the woods, and grabs Howard’s young son, Robbie, from the car. Howard rushes to rescue his son, but is too late. The family returns to the village to report Robbie’s murder. Howard returns to the church where the possessed Declan O’Brien informs him that centuries ago, they buried the devil alive deep in the dirt, but he survived. Declan declares, “The darks ones come back. They always do.” When Howard deduces that the creature depicted in the stained glass is the creature that killed his son, Rev. Coot dismisses the idea. A few moments later when Coot touches the chest on the altar, his hand is scorched, but he resists the demonic images that result from touching the chest. At the trailer park, Rawhead pushes one of the trailers over and pulls out one of the occupants. The other residents try to pull Rawhead off their friend without success. One of the residents ignites a gas canister, but the explosion does not affect the demon. Police search for Rawhead, who comes upon Detective Inspector Isaac Gissing and hypnotizes him. Rawhead goes to the church graveyard and Declan O’Brien kneels before him. Rawhead urinates on Declan to baptize him. Rev. Coot hides in the basement, where he discovers the missing parish records, containing drawings and instructions for destroying Rawhead. Declan finds Coot in the basement and proclaims that Rawhead is a god and used to be the king of the region, long before Christianity was brought to Ireland. Police surround the church, while Rawhead attacks Coot in the sanctuary. Rawhead carries the reverend outside and throws him onto a grave. Police are about to fire when the possessed Det. Insp. Gissing pours a canister of gasoline onto the road and lights a match, setting police cars ablaze. Gissing kneels at Rawhead’s feet. Howard Hallenbeck goes to the sanctuary and finds Declan has torn it apart. Declan tries to choke him, but Howard fights him off. Howard tries to open the chest on the altar, but the heat scorches his hand. He uses a candlestick to open the chest without touching it. Inside, he discovers religious trinkets and fertility symbols. He goes to the graveyard with the fertility statue, but it has no effect. Rawhead pushes him to the ground, then kills Declan. Howard’s wife, Elaine, picks up the fertility symbol, and it emits green beams which engulf Rawhead and push him into a grave. The fertility statue turns into the Virgin Mary. Howard realizes that it had to be a woman holding the fertility statue to activate the spell. After the villagers bury the dead, things returns to normal, but Rawhead emerges from the grave again.