In 2019, a local boy's disappearance stokes fear in the residents of Winden, a small German town with a strange and tragic history.

Bizarre occurrences give Charlotte a sense of déjà vu, and she suspects Peter is hiding something. Franziska snaps when Magnus confronts her.

Ulrich questions a frail and frightened Helge in the nursing home. Jonas searches for Mikkel, but the stranger warns him about meddling with the past.

In 1953, the disfigured bodies of two boys are exhumed at a construction site, the future location of Winden's nuclear power plant.

Ulrich runs afoul of the law, Helge tries to dodge Egon Tiedemann, Claudia harnesses the cave's powers, and Katharina lashes out at Hannah.

Peter gets a shock. Jonas learns the truth about his family, but there are more surprises still to come. Helge makes a sacrifice.

In 2019, Jonas emerges from the cave into a strange but familiar world: the town of Winden, reeling from the recent disappearance of a young boy.

Charlotte and Ulrich try to piece together what happened in the bunker. In different times and worlds, Jonas and Martha work to gain each other's trust.

Adam holds Martha captive in 2020. On the day of the apocalypse, an increasingly frantic Martha begs Bartosz for his help.

Claudia reveals to Adam how everything is connected — and how he can destroy the knot.