When an elderly woman opens the door to her storage room in the apartment building where she lives, she dies in a huge explosion. The woman is killed instantly. When Eva and Wolfs investigate, it turns out she is not the only death in the apartment building. Several residents appear to have died in the days before under very suspicious circumstances. A sinister serial killer seems to be at work, and the team finds itself in a race against time to try to prevent more victims. Marion has been given time off for a family member's funeral. It turns out very differently than expected, and before she knows it, she is caught up in a family feud. While Romeo gets to know a sex offender he is helping to reintegrate into society, Wolfs finally has time to go on a motorcycle tour with his friends. However, his friends turn out to have an appointment with another motorcycle club.

Maastricht is shaken by the disappearance of a nine-year-old girl near a busy shopping center. An Amber Alert is immediately issued and the entire police force is mobilized to find the perpetrator. Romeo, still enthusiastically volunteering in a group that helps sex offenders reintegrate into society, fears that the man he is responsible for has something to do with it. But Wolfs and Eva discover that the clues lead to someone else entirely. Meanwhile, Romeo is plagued by guilt. Eva tries in vain to get Tonja and her boyfriend to testify about a crime they witnessed within the motorcycle club. And Wolfs learns that the threat from Daan de Vos is much worse than he first thought.