Six years after quitting the Paris police force and abandoning the hunt for a serial killer, Rebecca is back on the job. And as she investigates a spate of brutal murders that all carry the same signature, she becomes convinced the killer has resurfaced. Obsessed with the case, betrayed by her husband, and hampered by both depression and crippling blackouts, she throws herself into work to avoid falling apart. But Rebecca’s attempts to track down the murderer only bring her demons to the surface. When one of the victims turns out to be her husband’s young mistress, Rebecca struggles to piece together the fragments of her erratic memory. And, as the evidence piles up, she is faced with the terrifying realization that she herself may be the culprit.