Two police officers discover a homeless man dead, beaten, in the abandoned building where he lived. Astrid and Raphaëlle immediately go there. At the crime scene, Astrid notes an intriguing detail: the victim is wearing a very clean suit, without any trace of blood. This enigma is quickly resolved: another homeless man, who shared the same squat, is arrested. He admits to having put the costume on him to attract the attention of the police. According to him, three other homeless people were killed in the same way without the police launching an investigation. Astrid, like Raphaëlle, is determined to stop the killer, but she does not know how much this investigation will weigh on her emotional stability...