Jack arrives at the forensics lab to start his day shadowing Harrison and is quickly impressed by all the equipment at Harrison’s disposal, especially a new photo enhancement programme. Harrison and Jack get called to a house where DS Tom Cooper informs them that the victim’s husband came home to find his wife Vicky dead in the kitchen.

When Cooper is sceptical about allowing Jack into the crime scene, Harrison vouches for him. Jack pales at the bloodied mess of the kitchen and the dead woman, but is fascinated as Harrison explains how he assesses a crime scene and watches as he gathers forensic evidence. When Harrison reveals Vicky was stabbed, Jack wonders if she could be another victim of The Scraper.

Cooper is worried they have no leads but Harrison points them to an apple with a bite out of it which has clearly not been done by Vicky. As Vicky’s body is taken out of the house, Harrison and Jack extract some DNA from the apple which has a match on the database. Seeing Vicky’s body at the morgue proves too much for Jack and he faints.

Back at the lab, Harrison and Jack try to recreate how Vicky was stabbed and find that she was stabbed by a left handed person. When someone confesses to the murder, Jack thinks their job is done, but Harrison says they must scientifically link the person to the murder. When the killer is caught, Harrison congratulates Jack on the contribution he made to the case.