A dead woman is fished up from the ocean; her name and origins are unknown. Forensics show that she had been tied up before being thrown alive into the sea. Her body is covered with hematomas, making it likely that she had been abused before her death. Searching for her identity, Clüver, Feldmann and Ina find out where the woman had spent the night, and whom she had shared it with: her friend Diana. But when Ina tries to interrogate her, Diana strikes her, takes her pistol, and escapes. Meanwhile the police have identified the victim as Claudia Gollnik. Delving into Gollnik's past, Ina visits an acquaintance of hers in Hamburg. Here she finds out that Gollnik had made a substantial inheritance on the upper-class island of Sylt not long ago. Clüver, in turn, meets the siblings Johan and Sabine Graskamp, who both claim that they don't know the victim. Feldmann also comes up with an important piece of evidence: the victim had been thrown into the sea from a private yacht. Now he's simply got to find it. But then Clüver gets drawn into the dark dealings of false heirs who are ready to kill to strike it rich on Sylt. At the same time, the police are increasingly worried about Diana, who still has Ina's pistol. Impelled by hatred, she wants to take revenge on the Graskamp siblings who are connected with a crime committed long ago. She doesn't realize how dangerous they are, however. When Diana confronts them with her accusations, she brings herself into danger. Clüver must now protect the main suspect – and himself – from the Graskamps.