Backtrack

An armed robbery leaves Inspector Kate Longton and Detective Chief Inspector Mark Perrin reading the same crime scene two different ways. Backtrack is a taut study in command structure, the kind of episode where the departmental politics are the drama and the robbery is the battlefield. Broadcast in December 1983 as the fourth series' closing episode, it leaves Longton's authority intact but dented, which is about as much as any commander gets at the end of a long year.

Perrin, played by Edward Peel, has his own ideas about how the scene should be handled, and Longton has hers, and the pair of them spend the hour pulling in opposite directions while the evidence waits to be read properly. The disagreement is professional rather than personal, exactly the kind that hurts most, with both of them sure they are right and the case hanging on the difference. Sergeant Joseph Beck, Sergeant George Parrish, PC Brian Kelleher and PC Danny Sparks keep the ground covered, DS Dick Maltby works the detail, and the robbery's world supplies William Minty and Vic Knight. John Holden hovers at the edges of Longton's life as the pressure builds.

Ian Kennedy Martin wrote it, Leonard Lewis directed. Anna Carteret is Kate Longton, with David Ellison as Beck, Noel Collins as Parrish, C.J. Allen as Kelleher, Mark Botham as Sparks and Tom Georgeson as John Holden. Edward Peel plays Detective Chief Inspector Mark Perrin, Sebastian Abineri is Detective Sergeant Dick Maltby, John Stratton is William Minty and Paul Angelis is Vic Knight.

The episode shows how differing perspectives, especially when adrenaline is involved, can create serious operational obstacles. It is police work grounded in departmental politics rather than action sequences, and it is all the more convincing for that.

A satisfying hour for anyone who likes their drama in the corridors. The robbery gets solved; the argument about how it was solved is the bit you remember.