On a misty autumn afternoon, a woman covered in blood clutching a baseball bat walks silently into a London police station. The two officers assigned to her case are DI Leah Hutch and DS Benjamin Randle. But the woman refuses to speak.

She is not injured and the blood on the bat is not hers. What has she done? Is she the victim or the perpetrator? As Leah and Randle start their inquiry, a man is found battered to death in a nearby park. Journalist Odie Reid receives a tip off and is determined to solve the case first, trying to link this death to the woman held in custody.

Leah and Odie have history and very quickly their cat and mouse game becomes personal, leading them both to the very darkest corners of their pasts.