It’s June 26, 1954. Egon and his co-workers inspect Claudia's corpse in the station's morgue. She is shown to have unusually high levels of radiation. Egon immediately recognizes her, saying that she had come into the police station before, apologizing profusely but making little sense otherwise, on the same day that the missing Helge returned. One of the other officers suggests that Egon show a photo of Claudia to Helge, to see if the young man could shed more light on just who the mysterious dead woman was. Shortly after arriving at the Doppler family home, Egon questions the boy. Helge says that while he doesn't know her, he has heard about her, calling her "the White Devil", and while he doesn't reveal his source for this information, he claims that Claudia "wants to kill everyone". Egon then points out that Claudia is dead, so she can't hurt anyone any longer, to which the boy responds, "...she hasn’t even begun yet."
In 1987, Claudia is sitting at her desk in her office at the nuclear power plant, recording her research findings. When she realizes that it's the day her father Egon is supposed to die, she hurriedly rushes out to see him. She continues to push him to move in with her, and Egon shows increasing reluctance to leave his comfortable apartment. Claudia, disheartened, then asks if she can come with him to his first chemotherapy appointment that day, to which Egon responds with heartfelt joy.
In the present: Martha, having found the St. Christopher medal (left by the adult Jonas) thinks Jonas has returned, as Bartosz predicted. She mentions this to her friends and she and Bartosz argue. She makes it clear their relationship is over. She heads off on her own to Hannah’s house. While Hannah isn’t there, the adult Jonas (The Stranger) is and lets her in. Martha asks who he is. She looks at him strangely and he asks if she is scared of him. She says she is experiencing deja vu. As he did previously, he responds "a glitch in the matrix." He asks whether she found the St. Christopher medal he left for her. She then realizes that he is Jonas. Sitting at the kitchen table he starts to explain his absence. Martha then says it all makes sense now. She takes his hand in hers and touches his forearm and face. They are interrupted by Katharina who breaks into the house, searching for Hannah. On seeing Martha and Jonas together she pulls them apart and asks Martha whether she knows who this man is: The son of her brother, her nephew. She tells Jonas to keep his dirty hands off her and takes Martha away.
Clausen closes in on Aleksander, stating he is being charged for identity theft and obstruction. He says he is looking for Aleksander Köhler, who is his brother. He says he believes his height is different to what his documents state and curtly states "you are definitely not my brother."
Hannah uses the time machine she stole from the adult Jonas (The Stranger) to travel back in time to 1954, asking to see Egon, stating she is looking for her husband who might be the man accused of murdering the children. She lies when asked about her name that she is Katharina Nielsen. Egon, slightly suspicious at the sudden appearance of a relative, eventually lets her visit Ulrich at the psychiatric institution, asking her to try to get a confession from him. Ulrich seems surprised to see Hannah. He asks about Mikkel, Katharina, Martha and Magnus. Hannah, sensing that he cares more about Katharina and his family, asks him who he would choose between her or Katharina or if he ever loved her. He tells her he loves her and will leave Katharina if she can get him out of there. But his words sound hollow and desperate, just in the hope she will get him out. She turns around as Ulrich is brought back, yelling in desperation, telling Egon that despite a slight resemblance, Ulrich is not her husband. Back in his office, he apologizes for not reacting sooner. He asks if she is leaving. Hannah states that she lost everything back where she came from and is looking for a fresh start.
Jumping back to 2020, at the Doppler house, Franziska, Magnus, and Elisabeth share what they know with Charlotte and Peter, who are actually already aware of the time traveling occurring. Once Franziska realizes that her parents are not surprised by the news about time travel, she gets angry that they kept this knowledge a secret, as well as her father's affair.
In 1987, Egon begins to tell Claudia that he knows time travel really exists. When he starts to put the facts together and realizes that Ulrich kept returning to the caves, Claudia grows increasingly hostile and defensive. He tells Claudia she knows about time travel too and it is connected to the power plant. He starts phoning the police to search the caves. Claudia stops him and says this is too important to be jeopardized. He tells Claudia she has no heart. They struggle over the phone and Egon falls backwards, cracking his head open on the table. Claudia calls an ambulance (which could have saved his life) but hangs up, remembering what her older self said about sacrifices and everything happening as it always has so Regina will live. Egon speaks his last words to his daughter: "You are the White Devil."
After leaving her father to die, she heads home, visibly distraught, and begins to wash the blood from her hands, sobbing uncontrollably. She is then startled as the teenage Jonas enters with a key but she does not know who he is or how he has a key. She realizes he must have got it from her older self. He tells her that they have to go and don't have much time. He knows what she did, but it doesn't have to happen again. Next time. "Where are we going?" she asks, "To the future," he responds.
- Adam: People are peculiar creatures. All their actions are driven by desire, their characters forged by pain. As much as they might try to suppress the pain, to repress desire, they cannot liberate themselves from eternal servitude to their feelings. As long as the storm rages within them they can find no peace. Not in life, not in death. And so, day after day, they will do all that must be done. Pain is their ship, desire their compass. All that humankind is capable of.
- Egon: Do you know this woman?
Greta: Answer the sergeant.
Egon: Were you with her maybe? Did she lock you in?
Helge: He told me about her. The White Devil.
Egon: Who? Who told you about her? The man who did that to you? The White Devil. Tell me about the White Devil.
Helge: She wants to kill us. All of us.
Egon: She's dead. She can't hurt anyone anymore.
Helge: But she hasn't even started yet.
- Aleksander: What is it?
Clausen: A copy of a document from the Marburg Registry Office, the data on your last ID before you left Marburg.
Aleksander: I've no idea how this is relevant.
Clausen: Nothing stands out?
Aleksander: No. What should stand out?
Clausen: You're 5' 6", I bet. Tops. That document says 5' 8". So I'm wondering where it is?
Aleksander: Where is what?
Clausen: The two inches missing.
- Egon: You were always different. You saw the world differently from the very start. Sometimes I think that that's my problem—that I can't see the world as it truly is.
- Clausen I have no idea what's going on in this town. But I'm very certain of one thing: you are definitely not my brother.
- Claudia: What's in the caves eclipses all scientific discovery. That substance turns all we know about the universe on its head. And you want to risk all of that? For nothing?
Egon: You haven't changed. It's still all about you. You have no heart.
- Hannah: I lost everything where I came from. All I want is a fresh start.
- Jonas: I know what you did. She told me. But she also said it didn't have to happen that way again, next time.
Claudia: Where are we going?
Jonas: To the future.
- The White Devil - Der weiße Teufel is a 1930 German film adapted from the Tolstoy novella Hadji Murat, in which the titular character forms an alliance with his enemies in order to exact personal revenge.
- The Matrix - In the 1999 science fiction film The Matrix, what humans perceive as reality is actually a massive computer simulation, and a feeling of déjà vu indicates a "glitch in the Matrix."
- Among the items found on Claudia's body is a pocket sundial, which can be used to estimate time and provide direction. This is the first time such a device has been depicted on the show.
- Aleksander Köhler's height is listed as 175 cm (almost 5'9"), and Clausen estimates Aleksander Tiedemann's height at 171 cm (a little over 5'7"). It is not clear why the subtitles use different measures.
- It is not clear whether Clausen knows that Aleksander stole the real Aleksander Köhler’s identity, or if the man he believed was his brother had changed too drastically to believe.
- Hannah had previously blackmailed Aleksander to destroy Ulrich and now does so herself.
- In the preceding episode Jonas asks Claudia who she is. In this episode Claudia asks the same of Jonas.
- Who wrote the anonymous letter to Clausen?
- Dietrich Hollinderbaumer as Adam
- Lisa Vicari as Martha Nielsen
- Andreas Pietschmann as The Stranger
- Maja Schöne as Hannah Kahnwald
- Oliver Masucci as Ulrich Nielsen
- Louis Hofmann as Jonas Kahnwald
- Jördis Triebel as Katharina Nielsen
- Daan Lennard Liebrenz as Mikkel Nielsen
- Sebastian Hülk as Egon Tiedemann (1953)
- Lisa Kreuzer as Claudia Tiedemann
- Florian Panzner as Daniel Kahnwald
- Stephan Kampwirth as Peter Doppler
- Karoline Eichhorn as Charlotte Doppler
- Sylvester Groth as Investigator Clausen
- Gina Stiebitz as Franziska Doppler
- Paul Lux as Bartosz Tiedemann
- Moritz Jahn as Magnus Nielsen
- Carlotta von Falkenhayn as Elisabeth Doppler
- Cordelia Wege as Greta Doppler (1954)
- Tom Philipp as Helge Doppler (1953)
- Christian Pätzold as Egon Tiedemann (1986)
- Peter Benedict as Aleksander Tiedemann
- Henning Peker as Pathologist Udo Meier
- Lea Willkowsky as Jasmin Trewen
- Leopold Hornung as Torben Wöller
- Mieke Schymura as Officer Justyna Jankowski
- → See 33 images from The White Devil at Images from The White Devil.