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 1954, a missing Helge returns, but he'll only speak to Noah. In 1987, Claudia brings the time machine to Tannhaus, and Egon questions Ulrich again.

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.

Martha and Jonas travel to 2052 and get a glimpse of a grim future. In 1954, two residents of Winden go missing, and Hannah receives surprising news.