In 2019, a local boy's disappearance strokes 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.

It's 1986 and Ulrich's brother, Mads, has been missing for a month; confusion reigns as past and present intertwine.

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

Hannah takes her obsession with Ulrich too far; the stranger asks Regina to deliver an important package; Martha is torn between Jonas and Bartosz.

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