Spoilers for this episode and earlier episodes.
In 1953, Egon catches Ulrich near the caves and arrests him over the missing Helge and the dead boys. Ulrich insists that he has changed events by attacking Helge, but the injured child wakes in the bunker. Greta seeks reassurance from Noah while the search for her son continues. At the Tiedemann home, Agnes grows closer to Doris, and Claudia remains concerned about her missing dog Gretchen.
In 1986, Gretchen appears in the caves and finds the adult Claudia. Bernd admits that an accident at the power plant released radioactive material that was concealed underground, with the workers paid to stay silent. A wounded newcomer rescues Regina from Katharina and Ulrich, then adopts the name Aleksander from a passport. His original papers identify him as Boris. Hannah sees him bury those papers and a gun, storing a secret she will later use against him.
In 2019, Katharina confronts Hannah, who lies about Ulrich's role in their affair. Hannah then blackmails Aleksander into helping her ruin him. Jonas turns Martha away without explaining their family connection, and Bartosz receives a visit from his elderly grandmother Claudia. In 1986, Helge questions Noah about their experiments, but Noah persuades him to continue building a time machine. An older Claudia visits Tannhaus in 1953 with plans for a device, while the Stranger retrieves material from the concealed barrels in 2019.