Christian and Dani, a young American couple, are having trouble with their relationship. After Dani suffers from a personal tragedy, the two of them decide to go on a vacation to rural Sweden with their friends, Mark and Josh, where they visit a small village that is hosting a festival held once every 90 years. Unbeknownst to them, the festivities are made up of violent and disturbing pagan rituals, and the locals insist that they join in.