After a veteran cop and a teenage girl fall to their deaths from a tower block in London’s East End, left alive on the roof are rookie police officer Lizzie Griffiths and a five-year-old boy. As DSI officer Sarah Collins sets out to uncover the truth behind the grisly deaths, the investigations that follow take her into the dark heart of policing in a complex and diverse city.

Sarah and Lizzie work together to hunt a killer. A new suspect emerges in the Tania case.

As the manhunt closes in on Brannon, Sarah realises where Tania’s body might be buried.

Lizzie and Brannon come face to face and Sarah finally tracks down Tania’s killer.