When 15-year-old Lynda Mann turns up murdered, DCS David Baker leads the investigation to search for her killer but struggles to find any worthwhile leads in the difficult case. Meanwhile, scientist Alec Jeffreys works tirelessly to make a breakthrough in DNA research.

The murder of another teenage girl killed in similar circumstances reignites the search for Lynda’s killer. After an arrest and a dubious confession, David approaches Alec and asks for his help on the case.

Possessing what they believe to be the killer’s genetic “fingerprint,” David and Alec initiate the world’s first “DNA manhunt.” But as thousands of samples are tested and costs continue to rise, David worries the operation will be shut down before they can find the killer.