Illegal body building drugs combined with mind bending additives cause a series of deaths around the muscle scene in Glasgow. In a race against time to find the source of the deadly drug the Maryhill team call on the help of a famous chemistry professor at the University. But is he helping or is he the source of the drug?

A school master is beaten to death with a cricket bat by an unknown assailant. 60 years later, the body is found by students on a cross country run. Douglas Flemming identifies the bones as Friedrich Zwanziger, a strict disciplinarian who disappeared while collecting beetles. As the investigation proceeds, McVitie discloses that he is on the board of governors.

An 'escort agency' woman is found brutally murdered in a hotel carpark. At the same time the daughter of a well known ex-army colonel goes missing. Are the two linked or is it just coincidence? While Jardine and Fraser try to unravel the mystery surrounding the murder and the disappearance, Jackie goes undercover at 'Executive Adventures' to keep tabs on the main suspect. But has Jackie's cover been blown and is her life in danger from the real murderer?