John Mottram, a cytologist at Newcastle University, firmly believes that the Black Death was not caused by bubonic plague, but by an unknown virus. He is delighted when the University of Oxford informs him that the bodies of victims from the Black Death have been preserved in the cellars of Dryburgh Abbey. Mottram sees this as a chance to prove he's right. At an excavation, having penetrated a secret tomb, Mottram loses his mind. Dr. Stephen Dunbar, an inspector at Sci-Med, is sent to investigate this case, fearing that a new killer virus will be released. Detective “Mutation” continues the series of medical thrillers by the world famous Scottish writer Ken McClure about the investigations of Dr. Stephen Dunbar from the Sci-Med agency. Med Inspectorate."