The privileged boys of St. Florian’s military academy are supremely confident in themselves. After being questioned by Oskar and Max in connection with the death of another student, Zelenka, they turn on their teacher Herr Lang, the only person at St. Florian’s who has willingly aided the investigation. Surrounding him threateningly, they warn him that they are going to spread a rumor that he abused one of them—he shouldn’t have given Oskar and Max their names.
Max doesn’t believe that Zelenka’s death was accidental, and goes to Amelia Lydgate for help proving it. Together they sneak into the morgue at the hospital where Max is studying, and Amelia takes samples from Zelenka’s corpse. As they leave, Max’s antagonistic professor watches from a window.
Oskar has returned to his house to discover that his wife—who has recently reappeared after a separation—has gotten rid of all of their deceased daughter’s possessions, which he was keeping in memory of her. You need to move on, she tells him. She didn’t leave because of their daughter’s death—she left because of Oskar’s obsession with it.
Max appears at Oskar’s house with something to distract him: he has had a realization about Zelenka. The dead boy’s sister asked Oskar and Max to retrieve a portrait he was painting at St. Florian’s, but Max has remembered that St. Florian’s doesn’t offer art lessons, even though Herr Lang is an artist. Zelenka must have been taking private lessons with Lang.
Oskar and Max visit Lang and ask where the portrait is. Lang feigns ignorance, but a flick of his eyes points the investigators to a painting in progress. Underneath the canvas, they find Zelenka’s portrait. It is of a young woman, whom Oskar recognizes seeing outside a cottage on the grounds of St. Florian’s.
Visiting her, they learn that she is the daughter of Becker, the school’s chemistry and biology teacher as well as its medical officer. She pretends not to know Zelenka or about his portrait—she is not supposed to interact with the school’s boys. Eventually, she admits that Lang asked her to sit for Zelenka. Right then, Becker himself appears and dismisses Oskar and Max: Zelenka must have been a secret admirer; his daughter is not involved in the boy’s death.
Oskar returns home and apologizes to his wife. You were right, he tells her; he has to move on from their daughter’s death.
Max’s parents choose a disastrous moment to try to effect a similar reconciliation between him and Clara, his ex-fiancée. Amelia has come to the Liebermann home to report that she could not find any traces of murder on Zelenka—his body sat in water for too long. Max invites her to stay for tea. As they are sitting down at the already-set table, Clara appears: Max’s parents have asked her over. Amelia tries to excuse herself; Max insists she stay. The conversation quickly spirals out of control, Clara tells Max to “go to hell,” and by the time his mother appears at the table to meet Clara, she has stormed out. Needless to say, Max’s parents are not happy.
Back to the investigation. Max wonders how Daniel knows the St. Florian’s prayer when he is Jewish—the boy has recited it when Max tries to question him about Zelenka. Max realizes all the boys know it by heart, since it is hung on the walls of their dorms—and decides that it must be the key to breaking the code on the note found amongst Daniel’s things at the school. Max and Oskar decode the message: “Prove yourself worthy. Choose Zelenka.”
It seems the St. Florian’s boys’ sadistic initiation ritual, in which they press a burning coin into a boy’s palm, passes from student to student. Max and Oskar will try to catch the boys in the act.
The night they choose features a more dangerous form of the ritual than before: Russian roulette. We’re going to teach you courage, one of the older boys tells the initiate, before making him put the gun into another boy’s mouth and telling him to fire. Luckily, the police appear just then and the boys scatter. Oskar and other policemen grab some as Max chases after the ringleader, Wolf, eventually cornering him in the dorm.
Wolf tells Max that the ritual is tradition; he will never be able to stop it. Max punches him just as Oskar catches up. The youngest boy from the ritual appears, crying as he points the gun at Wolf. Max tries to talk him down, and finally Oskar gets close enough to snatch the gun away.
The next day, the commissioner chastises Oskar: Wolf’s father, a general, has complained about excessive force used on his boy. Oskar accepts full responsibility, despite his chance at a promotion.
Now that Max knows the full extent of the St. Florian’s ritual, he is able to get Daniel to talk. The boy tells him that it was his turn to bring a boy to a ritual, and he was ordered to bring Zelenka. But Zelenka ran into the woods after being burned and the other boys chased him, afraid he would expose the ritual. They cornered him at the river—and then Zelenka suddenly began choking. He died in front of them, without any of them touching him. Afraid they had caused his death somehow, the boys threw his body in the river and buried his cape.
With Daniel’s help, Oskar and Max dig up the cape. They bring it to Amelia, who quickly discerns a trace of cyanide gas on it—someone poisoned Zelenka.
Max realizes that the letter to a beloved found in Zelenka’s locker wasn’t Zelenka’s; he was just the messenger. He was running letters between Becker’s daughter and her true lover: Herr Lang. Becker suspected his daughter was having an affair, but chose the wrong culprit. He decided to punish the perpetrator, offering Zelenka a quiet place to work in the chemistry lab and running an experiment that generated cyanide gas while he was there.
As Oskar and Max confront Becker in the lab, he smashes some vials and runs. He leads them to the top of a tower and climbs up onto the ledge. Telling them that his daughter will remember him as a man of honor, he falls backward to his death.
The next day, the commissioner tells Oskar that the school may not survive the scandal. He also reveals that von Bülow, a graduate of St. Florian’s, has been promoted over Oskar. Showing Oskar a scar in the palm of his hand, the commissioner reveals that he, too, attended St. Florian’s.
The case has also affected Max’s professional prospects: his professor has suspended him for sneaking Amelia into the morgue.
But worse disappointment awaits Oskar. When her returns home, his wife is gone—and she has left her wedding ring.
The devastated Oskar tells Max that he must grab any chance at happiness he can get; if he loves Amelia, he should be with her. Feeling alone in the world, Oskar asks Max if he really thinks of him as a friend. Max responds: “Tell me, inspector, what’s our next case?”