Set in 1984, Code of a Killer is a true story which tells of the discovery of DNA fingerprinting. Detective David Baker leads an investigation of the vicious murders of the two Leicestershire schoolgirls, Lynda Mann and Dawn Ashworth. Alec Jeffreys at the time was an ambitious scientist who uncovered a remarkable method to read each individual's unique DNA finger print. Convinced the murderer was local, Baker approached Jeffreys to utilise his newly discovered scientific technique as a way to solve the murders. The first ever DNA manhunt and blood testing of many men followed - all in the aid of catching the killer.