In their quest to solve what originally appears to be a case of misplaced baggage involving an innocent student, detectives Massey and Turner are drawn into a complex web of deceit. The action takes place in and around central London as their team attempts to discover into what crime, if any, they have stumbled by accident.

A kidnap followed by a ransom demand leads to a dramatic chase on the river Thames involving stolen cruisers. A bungled police operation and lack of forensic evidence frustrate the two detectives as they seek logical answers to a series of seemingly unrelated events. As the mystery unravels they realise that some highly professional criminal activity is taking place, leading their enquiries to northern France.

When two suspects are assassinated in St. John's Wood and Primrose Hill, a murder hunt ensues. Further revelations indicate the awesome possibility of a potential bio-terrorism threat, resulting in personal problems for both the inspector and his sergeant.