My Bloody Valentine (1981)

There's a big valentine-party planned in the little coal mining town of Valentine Bluffs, Nova Scotia. It is the first Valentine's Day party in 20 years, because then there was an accident in the mine, and the accident happened because the men responsible for the security was at the party. The sole surviving miner, named Harry Warden, later killed them, and told the town NEVER to arrange a Valentine's Day party again. The party begins, and so does the killing...