Anna Hopkins' daily walk through Oxford's picturesque Port Meadow is rudely interrupted one autumn morning when her white German Shepherd, Bonnie, unearths a bloodsoaked body in the undergrowth. For Anna it's a double shock: she'd met the victim previously. Naomi Evans was a professional researcher who had told Anna she was working on a book about a famous Welsh poet, and who offered to help Anna trace Bonnie's original owner.

From her conversations with Naomi, Anna is convinced that she was not the random victim of a psychopathic serial killer, as the police believe. She was targeted because of what she knew. With the official investigation heading in the wrong direction entirely, Anna teams up with fellow dogwalkers Isadora Salzman and Tansy Lavelle to discover the truth.