The series begins with a woman who has been brutally stabbed in her home in Leeds. Over the course of the critical next few hours the teams and blood-analysis experts meticulously assess the scene to establish what might have happened and report back to the detectives investigating the case.

Forensics are called to a terrifying scene at a family home: 33-year-old man has been fatally stabbed in his kitchen. Police embark on a huge manhunt to find who is responsible.