With DI Mike Nash away on compassionate leave, DS Clara Mironova and the Helmsdale team are faced with a sudden and dramatic increase in crime. Minor offences ranging from theft, shoplifting, and poaching, pale into significance when a violent turf war breaks out between rival gangs of drugs suppliers.Within weeks the detectives have to cope with three murders, including the shooting of a police officer. As they struggle to investigate the killings, a batch of deliberately contaminated heroin hits the streets, resulting in the deaths of three addicts and causing panic in the media.The breathless speed of events puts the entire region on high alert. The detectives must capture the drug barons, break up their supply networks, solve the murders - and thwart the criminal mastermind before he can realize his ultimate ambition.