In the small mining town of Harmony, a tragic accident occurs on Valentine's Day, resulting in the deaths of five miners due to the negligence of their supervisor, Tom Hanniger. The sole survivor, Harry Warden, falls into a coma, only to awaken one year later on Valentine's Day, seeking revenge. Warden goes on a rampage, brutally murdering 22 people with a pickaxe before being killed by the police. The town is left scarred and vows never to celebrate Valentine's Day again.

Ten years after the massacre, Tom Hanniger returns to Harmony, struggling with the guilt of his indirect role in the tragedy. His arrival coincides with a series of gruesome murders that mirror the previous killings, causing panic among the townsfolk. The community is torn between the fear of the past repeating itself and the suspicion that the real killer might be among them. As the Valentine's Day dance approaches, the town becomes a pressure cooker of suspicion and paranoia, with everyone wondering if Harry Warden has returned from the grave or if a new killer has taken up his mantle.