On the day of the apocalypse, Clausen executes a search warrant at the power plant as Jonas and Claudia use the time machine to connect past and future.

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.

Armed with a plan to prevent the apocalypse, Jonas travels to 2019. During the Nielsens' anniversary party, Ulrich sneaks off with Hannah.

In 1987, Ulrich seizes an opportunity. The kids return to the cave with the time machine, and Jonas learns of a loophole that could change the future.

Jonas meets an ominous figure. While the kids comb the cave for answers, the adults gather in the bunker to share what they know about the travelers.

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.

Clausen and Charlotte interview Regina. The Stranger takes Hannah to 1987, where Claudia has an unnerving encounter and Egon visits an old nemesis.

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