Detective Chief Inspector James Hardy is enjoying a rare day out with his two young daughters when he makes the mistake of answering his phone— it’s his boss. A young mother, out walking her baby, has been murdered in broad daylight. Followed quickly, by a second terrifying, vicious attack on a young woman who’s a family friend of Hardy and his daughters. Shaken and heartbroken, Hardy assists the team leading the investigation into a killer dubbed, the Regent's Park Ripper. Knowing that in all likelihood the killer will soon strike again, the investigating team must put aside their differences, and work day and night to prevent more loss of life.