Kim and her boyfriend Matt have just broken up, but they travel together to a cottage nearby a lake to spend the weekend with their friends Eve, Dash and his wife Amber and Baker and his new girlfriend Lily. The atmosphere becomes heavy with the situation between Kim and Matt, and one of them suggests them to play "Dead Mary". Matt, Eve and Dash summon the evil witch repeating her name three times in front of a mirror with a candle. Along the night, Matt hears weird noises, is killed and returns to life, while part of the group is possessed by the fiend. Without knowing who is possessed, the rest of the group fights to survive.