Seven trauma survivors share their darkest secrets in a weekly support group. One of them is using those secrets to kill. When members of The Circle begin dying in ways that mirror their original traumas - stabbed in the same places, stalked with the same methods, terrorized until their hearts stop - Detective Christine DeLuca faces an impossible investigation. She knows the victims. She knows their vulnerabilities. She knows exactly how the killer is choosing them. Because Christine is a member of the group. Attending under a false name, hiding her badge, she has spent seven months sharing her own trauma alongside the people now being hunted. The killer sat beside her every Thursday. Held the same stone. Spoke the same pledge. Listened with what looked like empathy and was something else entirely. In a room where everyone is wounded, who is collecting the wounds?