James and Olivia Custer live with their children in the small American town of Meinriton. Their house has a tense atmosphere, constant scandals and mutual hostility. But the Custers' secret dream is to bring back the happy family they once were. Everything changes when Eddie's youngest son buys a chest with strange inscriptions at a garage sale. Having opened it, the Casters will no longer be the same. They have to answer the main question: what is evil in our world - a monster lurking in darkness, or endless darkness hidden in the soul of each of us?