Ten years ago, Dennis's daughter Ava vanished during a trip to the town of Paradise Falls. Since that day, he has been haunted by intrusive thoughts and the terrifying suspicion that he was responsible. When Ava's childhood drawings mysteriously reappear — defaced with cryptic messages — Dennis is drawn back to the now-submerged ruins of the town. In this watery purgatory, he encounters a congregation of zealots led by a radical pastor and a reality that shifts based on his own anxiety. To find Ava, Dennis must survive the town's grotesque inhabitants and decide once and for all if he is a father seeking redemption or a monster facing his final penance.