This episode starts with the interrogation of the number one suspect. With no body, it takes all the detectives' skill to prove the case and charge their suspect.
Forty-six-year-old Stephen Wallace is found dead in his Paisley home from a number of injuries. The detectives forensically comb the crime scene for clues which will lead them to his killer.
Detectives take on a decades-long mystery when they reinvestigate the 1984 murder of Mary McLaughlin. A new suspect comes to the fore, but it raises more questions than answers.