Case 1: Leicester, 1986. The body of 15-year-old Dawn Ashworth is found following her disappearance. The murder is almost identical to the killing of Lynda Mann in 1983. Detectives in charge call on the help of Professor Sir Alec Jeffreys who had just discovered the DNA fingerprint. The police obtain the killer's DNA and the hunt is on to catch him before he can kill again. Case 2: In March 2016 Jess convinces her best friend Laura to join her and members of her running club on a Monday night jog. Little did the girls know that also on the road that same night was a courier transporting a deadly package. The man loses control of his vehicle and hits the girls, leaving them fighting for their lives.