Lucienne’s relationship with another woman has fallen apart, and she’s feeling lonely. So she calls Van der Valk, and they end up spending the night together. So when Brad and Job come to Van der Valk’s boat to tell him a woman has been found dead in a hotel room, Brad is eager to spread the gossip about Van der Valk and Lucienne.
Aamina Jabara, the dead woman, seems to have had a strange night. She was strangled to death, a shallow cut in her side has traces of saliva, and there’s ayahuasca in her system, which explains the vomit in the hotel room: the drug causes retching before it induces a spiritual experience. The hotel room was booked under the name of a long-dead alchemist, and they also find a book from the Gilbert Library, an institution devoted to mysticism.
Aamina visited the library a few times a week, viewing books of medieval religious erotica. The same books were also frequently viewed by a Sister Catherine, but the address the nun listed is fake. Job and Brad track her down in a convent and learn that her name is actually Sister Joan. She defends her interest in the erotica and says that she became friends with Aamina at the library. Aamina became interested in the library as a way to rebel against her strict Muslim father, and learned of the erotica from a man whom she sometimes met for rendezvous at an Airbnb.
Job has already visited Aamina’s family. Her brother blames her death on their father, who recently drove Aamina away. Her father doesn’t even know that Aamina quit her job as a nurse to work at an addiction clinic with a radical treatment method.
At the clinic, which is run by a doctor named Isaak Graaff, Van der Valk and Lucienne show a patient a photo of Aamina and learn that she had a relationship with an addict named Otto. They don’t have an address for Otto, who did time for stabbing a dealer, but they do have a photo.
Brad goes to look for Otto in known drug haunts while Van der Valk and Lucienne visit the Airbnb Aamina used to meet a man—Sister Joan shared the address. As they ring the bell, Van der Valk notices a woman watching them before walking away. He follows, but she runs and escapes onto a bus. As it pulls away, Van der Valk glimpses her face—she looks just like Aamina.
Job has discovered that Aamina had a twin sister named Zafira. Not only that—Zafira is the dead woman, not Aamina. Zafira had a tattoo that matches one on the corpse. Her father must have purposefully misidentified the body. Why? He and Zafira had a falling out some three years ago, kicked off by her tattoo, and he was glad that his favored daughter was still alive.
Zafira had been arrested on a minor drug offense but was cleared. She did, however, seek treatment at the Graaff clinic, and as part of that treatment reconnected with Aamina. That’s why Aamina began working at the clinic. Like Zafira, Aamina had recently left home after an argument with her father, over a relationship. But now he wants her home, and has asked her brother to call her and tell her he apologizes.
The Airbnb is found to have traces of ayahuasca, and was booked in the name of a pseudonym of the same alchemist listed as the renter of the hotel room. Turns out that Klaas Gilbert, the wealthy industrialist behind the mysticism library, has written a book on this alchemist. Furthermore, despite Gilbert’s spiritual focus, he has made his fortune manufacturing weapons, and is known to keep a gun in his desk.
Job also realizes that a scholar who just gave a talk at the library on a cult that worships the wounds of Jesus—the cut on Zafira’s side mimics one of the wounds—is staying at the hotel where Zafira was killed. Van der Valk decides to talk to him at a rare book sale hosted by the library that evening.
Another person of interest will be there, too. Brad has found Otto at a pub. He’s on a video call with Aamina, who tells him to meet her at the book sale. Brad approaches Otto, who kicks him and runs away.
It turns out Otto was involved with Zafira, not Aamina: he was with her when she was arrested on the minor drug offense, and they were treated at the clinic together. Zafira did manage to get clean there.
Aamina was in a different relationship, as Lucienne discovers from reviewing the library’s security footage. Her friendship with Sister Joan eventually turned romantic: Lucienne sees them kissing in the library. That’s how Sister Joan had the Airbnb address: she had been there with Aamina.
Sister Joan, along with nearly everyone else of interest in the case, attends the rare book sale, as does Van der Valk’s whole team. Van der Valk learns from the scholar that adherents of the cult he researches might suck the blood of a wound mimicking Jesus’s—explaining the saliva on Zafira’s cut. Otto arrives and begins yelling at Klaas Gilbert, accusing him of murdering Zafira and seducing both her and Aamina. He pulls a knife, and Van der Valk and his team surround him, trying to talk him down. Suddenly, a shot rings out and Otto falls, dead.
The police quickly lock down the library to search for the shooter. They find a gun in a trashcan. Van der Valk questions Gilbert: are Otto’s accusations true? Gilbert denies even knowing the Jabara sisters, and shows Van der Valk a tunnel in the basement that the shooter could have used to escape—it’s a matter of public record, so anyone could have known about it.
After the disaster at the library, Aamina finally shows up: she has returned home to her father. She tells the police that she video-called Otto because she thought Gilbert was involved in her sister’s death. She confirms Otto’s accusation that both she and Zafira were involved with Gilbert, and that Zafira took ayahuasca with him. Zafira had Aamina’s ID on her because Aamina was trying to help her rent a car, which she couldn’t do with a drug offense on her record. Aamina also lent Zafira a book from the library because Zafira was interested in getting another tattoo and wanted ideas, hence the book in the hotel room.
A fingerprint test of the gun used to kill Otto seems to confirm this account: Gilbert’s fingerprints are all over it. He says it’s his gun from his desk, which he has for security but has never fired. He denies all the accusations—but Van der Valk has found a news piece about Gilbert being an ayahuasca shaman. Gilbert says he hid that fact because the indigenous community that taught him the ayahuasca ritual doesn’t like the world to know about Westerners who can administer the drug.
Something about Aamina’s behavior also doesn’t make sense. On the night when Zafira was killed, Aamina sat in a different place than typical at the library and also unusually left a manuscript out and said goodbye to the curator. Van der Valk brings her in to see if she can identify Sister Joan in a line-up—she seemed shocked when he brought up her affair with the nun. She doesn’t even recognize her lover.
That’s because she is Zafira. Aamina is the one who was murdered after all. Even though the corpse has the correct tattoo, it’s only about three weeks old—not three years. When Van der Valk confronts Zafira, she insists she is Aamina, but her brother doesn’t believe her—her behavior is wrong. Her father refuses to believe it—but Zafira’s fingerprints are on the manuscript checked out at the library the night of the murder, not Aamina’s.
So it was Zafira who visited the library, which means Aamina could have been killed earlier than previously believed—which means Isaak Graaff’s airtight alibi no longer holds up. Plus, Job has learned from the scholar who gave a talk at the Gilbert that he saw Graaff entering the hotel around the time when Aamina may have been killed—he recognized him because Graaff and Gilbert had a very public spat, since Graaff is an arch-rationalist who denounces all forms of spirituality.
Van der Valk convinces Zafira’s father to forgive her, and she finally admits her part in the scheme. She wanted to come home, and Graaff offered to help. He would kill Aamina and frame his enemy Gilbert so that Zafira could pose as Aamina and be accepted by her father. She convinced Otto to confront Gilbert to further the ruse—plus, Graaff considered Otto a loose cannon and wanted him dead. Graaff shot Otto with Gilbert’s gun while wearing gloves, then escaped through the tunnel. But the gloves were the ones he wears at the clinic, and had traces of tinfoil on them from the clinic that were found on the gun.
In the wake of this confession, Zafira’s father once again turns on her—you’re still dead to me, he says, and walks away. Faced with the evidence against him, Graaff tries to flee Van der Valk and ends up on the roof of the clinic, contemplating suicide. Van der Valk manages to talk him down. This time, he won’t lose his culprit.