Who is Sam in Nocturne? Jurek Walter answered that in court years ago

Apple TV's Nocturne premiered on October 30, 2026, with Stephen Graham as the imprisoned serial killer Jurek Walter, Liev Schreiber as Jonah Lynn, the detective who caught him, and Zazie Beetz as FBI agent Saga Bauer. Rowan Joffé created the series and John Hlavin runs it, adapting Lars Kepler's The Sandman and Lazarus and moving the story from Stockholm to small-town Pennsylvania. The 10 episodes run weekly through December.

A few episodes in, one name keeps coming up in flashbacks and in Jurek's taunts: Sam. The show is taking its time explaining him. The books spelled it out on the day Jurek was sentenced.

Sam in the show

Here's what the first two episodes establish, as Decider's Sean T. Collins recaps:

• His job: Sam Mendel (Gabe Fazio) was Jonah's friend on the force and his partner on the Jurek Walter case.
• His family: He's Saga's father, and he was married to Rebecca.
• His problem: Jonah calls him a good guy, but he drank on the job and was violent at home.
• His breaking point: In an episode 2 flashback, Jurek starts needling Sam about abusing Rebecca, whose name he somehow knows, and Sam has to be pulled off him.

Rebecca later disappeared while Jurek was already in custody, and Sam took his own life not long after. Jonah has always suspected Jurek had an accomplice outside. Then Michael Frost, who resurfaces after three years missing, mentions a woman named "Becky" who looked after him and his sister in captivity, with the same eye condition Rebecca had.

What Jurek said in court

In Kepler's The Sandman, Sam is Samuel Mendel, Joona Linna's partner, and the two of them catch Jurek together. After Jurek is sentenced, he calmly tells Joona exactly what's going to happen next: first, Samuel's wife and two sons will disappear. Then Joona's wife and daughter. Then both detectives will kill themselves.

Neither man takes the threat seriously until Samuel's wife and sons vanish. Samuel kills himself. Joona realizes he's next, fakes his own family's deaths and sends his wife and daughter to Helsinki under new names, with no contact.

Jurek Walter didn't hide what he had planned for Sam. He announced it in court, and then someone outside carried it out.

What the show is changing

Nocturne has kept the pattern and rearranged the family. TV Sam has a daughter, and she's the one going undercover. Saga is checked into Riverside Psychiatric as a patient, in the cell next to the man at the center of her father's last case.

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Jurek's courtroom moment is also pointed somewhere new. On the show, he claims Jonah lied at his trial and offers to help find Michael's missing sister, Felicia, only if Jonah admits it. Whether that's a ploy for a mistrial, as Jonah thinks, or the show's version of the book's courtroom threat is one of the season's big open questions.

In the book, the second name on Jurek's list was Joona's own family. Nocturne hasn't told us yet who's on Jonah's.

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