The story of the hunt to find the killer of two teenage girls in 1980s Leicestershire which led to an extraordinary forensic breakthrough - DNA fingerprinting.

Shocked by the failure to convict her daughter’s killer, a mother fights for justice by taking on the legal establishment and overturning an 800-year-old law.

The story of how a 1970s miscarriage of justice involving three teenage boys would lead to a radical overhaul of police powers and a brand new method of investigation.