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

When a grim discovery leaves the police baffled, Ulrich seeks a search warrant for the power plant. A mysterious stranger checks into the hotel.

Ulrich looks to the past for answers and dredges up disturbing family secrets. Armed with new tools, Jonas probes the cave's murky depths.

Six months after the disappearances, the police form a task force. In 2052, Jonas learns that most of Winden perished in an apocalyptic event.

Martha meets the Stranger and learns his true identity. Claudia tries to prevent Egon's death in 1987. Hannah travels to 1954 to see Ulrich.

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.