I 2019 fører en lokal gutts forsvinning til frykt og usikkerhet hos beboerne i Winden, en tysk småby med en merkelig og tragisk historie.

Når en grufull oppdagelse fører til full forvirring hos politiet, ber Ulrich om en ransakingsordre til kraftverket. En mystisk fremmed sjekker inn på hotellet.

Det er 1986, og Ulrichs bror, Mads, har vært forsvunnet i en måned. Forvirring råder når fortid og nåtid veves sammen.

Bisarre hendelser gir Charlotte en følelse av déjà vu, og hun mistenker at Peter skjuler noe. Franziska tenner på alle pluggene når Magnus konfronterer henne.

Hannah drar besettelsen med Ulrich litt for langt. Den fremmede ber Regina om å levere en viktig pakke. Martha slites mellom Jonas og Bartosz.

Ulrich ser etter svar i fortiden, og avdekker foruroligende familiehemmeligheter. Bevæpnet med nye verktøy, vandrer Jonas inn i hulens dunkle dyp.

Ulrich leter etter svar hos en svak og redd Helge på sykehjemmet. Jonas leter etter Mikkel, men den fremmede advarer ham mot å grave i fortiden.

I 1953 graves de vansirede kroppene til to gutter opp på en byggeplass, stedet hvor Windens atomkraftverk senere oppføres.

Ulrich havner på kant med loven, Helge forsøker å unnslippe Egon Tiedemann, Claudia prøver å utnytte hulens krefter og Katharina angriper Hannah.

Peter har en sjokkerende opplevelse. Jonas får vite sannheten om familien, men det er fortsatt flere overraskelser i vente. Helge ofrer noe.

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

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

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.

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 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.

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

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.

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.

In 2019, Jonas emerges from the cave into a strange but familiar world: the town of Winden, reeling from the recent disappearance of a young boy.

Martha travels to 1888 to warn her friends about the 2020 disaster. Winden residents past and present search for their missing loved ones.

Charlotte and Ulrich try to piece together what happened in the bunker. In different times and worlds, Jonas and Martha work to gain each other's trust.

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.

In 2020, a visitor delivers a warning to Claudia. The day before the apocalypse, Jonas begins to question Eva's motives.

Adam holds Martha captive in 2020. On the day of the apocalypse, an increasingly frantic Martha begs Bartosz for his help.

Across three centuries, Winden's residents continue their desperate quest to alter their fate and save their loved ones.

Claudia reveals to Adam how everything is connected — and how he can destroy the knot.