The pool of suspects shrinks in the wake of neighborhood tragedy. Karen offers Nora a way out. A strange visitor tells Dean about the Fourth Turning.

As Dean digs deeper into the house's history, Theodora discovers Dakota's disturbing screen name - and Ellie's secret relationship comes to light.

Nora thinks Dean wrote the letters to scare her into selling, but a DNA test yields surprising results. Contractors uncover something in the basement.

Dean and Nora find a hidden room where someone's been living. Theodora shares intriguing intel about Roger Kaplan. The family makes a fateful decision.

Nora urges Dean to move on, but the past continues to haunt him. A shocking confession doesn't add up. Back at the house, keen eyes continue to watch.