Contains spoilers for this episode and earlier episodes.
On the day of the alternate world's apocalypse, Martha returns home after watching Jonas die. She tries to warn Magnus, then asks Bartosz to stop Aleksander opening the radioactive waste containers. Aleksander has just admitted to his son that he is really Boris Niewald, linking his assumed identity to an old murder investigation. Meanwhile, Charlotte tells Ulrich that the coins found with Helge and in the bunker are identical. Ulrich releases Helge and follows him into the caves, hoping to explain Mads's death.
Adult Magnus and Franziska arrive from the original world and intercept Martha and Bartosz before they reach the plant. They tell Martha that Jonas is alive in their world and that she must save him from its apocalypse. She leaves with them, while Bartosz remains behind. Eva separately explains to the scarred Martha that the rescue is a branching point: in one version Martha takes Jonas to her world, where he dies, and in another he survives in his own world.
In the original world's post-apocalyptic Winden, Claudia finds the God particle and encounters the surviving younger Jonas. Decades later in that world, Adam restrains the pregnant Martha who followed his orders. He plans to focus the energy of both apocalypses on her unborn child, believing this will erase the knot. Eva sends her followers to maintain their family histories, while the cleft-lipped trio operates the power plants in both worlds. The alternate apocalypse erupts as Adam activates his machine around Martha.