Series 4

Now promoted to Detective Chief Inspector, Bulman, frustrated with the office-bound nature of the job, is soon challenged by an intriguing murder case.

A convict makes a daring prison break but leaves a trail to ensure his recapture is handled by the inter-city squad. He has an old score to settle with supervisor Lambie.

A routine assignment — escorting a prisoner from Glasgow to London — turns into something altogether different when the woman escapes and her escorts on a merry cross-country chase.

The squad investigates a series of armed robberies committed by a gang of modern-day highwaymen.

Bulman and Willis arrest a man carrying an incriminating roll of film. This triggers off an enquiry which takes them to Edinburgh, where they tangle with a gang specialising in political blackmail.

The squad investigates a murder and a series of knee-cappings committed by rival groups of mercenaries.