Description
Inside a mine shaft, a female miner takes off her gear in front of another miner. When the woman performs a striptease, the miner pushes her onto a mining pickaxe, killing her.
Mayor Hanniger of Valentine Bluffs, a Canadian mining town, reinstates the traditional Valentine's Day dance, which has been suspended for twenty years. The dances stopped after an accident in which two supervisors left several miners in the mines to attend the dance. Because they forgot to check methane gas levels, there was an explosion that trapped the miners. Harry Warden, the only survivor, resorted to cannibalism to survive and went insane. The next year, he murdered the two supervisors who left them there and vowed further attacks if the Valentine's Day Dance ever occurred again. Warden was placed into an asylum and the accident was forgotten, so the dance resumed. A group of young residents is excited about the dance: Gretchen, Dave, Hollis, Patty, Sylvia, Howard, Mike, John, Tommy, and Harriet. Sarah, Axel, and the mayor's son T.J. are involved in a tense love triangle.
Mayor Hanniger and the town's police chief Jake Newby receive an anonymous box of Valentine chocolates containing a human heart, and a note warning that murders will begin if the dance proceeds. That evening, resident Mabel is murdered by a mining-geared killer in a laundromat, and her heart is removed. Newby publicly reports that she died of a heart attack to prevent a panic. He contacts the mental institution where Harry Warden was incarcerated, but they have no record of him. Hanniger and Newby cancel the dance but the town's youngsters decide to hold their own party at the mine. A bartender warns them against it but is killed by the miner.
At the party, the miner brutally kills Dave; his heart is subsequently found boiling in a pot of hot dogs being prepared in the kitchen. Shortly after, Sylvia is impaled on a showerhead by the miner. When the others realize Dave and Sylvia have been murdered, they contact authorities, but several of the partygoers have already decided to enter the mines for fun. Newby rushes into the mines with police to rescue them. The miner impales a large drill into Mike and Harriet and shoots a nail gun into Hollis's head. Horrified, Howard flees. The remaining four try to climb to the top with a ladder but discover a dead beheaded Howard.
While finding their way out, Axel and Patty are killed by the miner. The miner chases T.J. and Sarah and a fight ensues. The miner is revealed to be Axel, who faked his demise. A flashback shows that Axel's father was one of the supervisors. As a child, Axel witnessed Harry Warden murdering his father, which traumatized him. Sarah hits Axel with a rock, resulting in the tunnel collapsing, which traps Axel as Newby and the police arrive to rescue T.J. and Sarah. The police explain to them that Harry Warden died five years earlier. T.J. and Sarah hear a rescuer shout that Axel is still alive, and they rush back to the scene. They watch as Axel frees himself from the debris by amputating his trapped arm. He runs deeper into the mine shouting threats to murder everyone in town, and mumbling about Sarah being his "bloody valentine". The film ends with a maniacal laugh being heard (either Axel or Harry Warden's) as a ballad for Harry Warden plays over the film's credits.
