The Wheeler Dealers

Unit 23 works undercover at Manchester's docks, trying to identify the ringleaders of a gang shipping stolen bicycle parts out of the country for assembly and export abroad. The work is dull and repetitive, and the three officers operate as dock labour while they watch and listen. Then they collide with a second operation already watching the same docks: a Special Branch team working to its own agenda and disinclined to share it. Bulman's people do not know the Special Branch officers are there. The Special Branch officers do not know Bulman's people are police. Two undercover parties are watching the same dock and neither recognises the other, which makes the danger come from a misunderstanding between police rather than from the criminals.

A second complication comes from the gang. One of the men involved recognises Doran from her earlier service in the Royal Ulster Constabulary, so her cover, which depends on her being a stranger in the city, is weaker than it looks. At the station, Rainbow is increasingly frustrated by the unorthodox methods of the unit he nominally oversees. His officers are not where he expects them, they do not report to him as he wants, and the episode returns repeatedly to the friction between policing from an office and disappearing into a patch to work from the inside.

This is the first episode made entirely on film, after a first series shot mainly on tape, and the change shows in the exteriors. The docks and the derelict industrial site where the pursuit ends have a weight that videotape location work did not carry. The chase finale is staged as a scramble rather than a controlled operation, and the mediagems guide's complaint that a capable stunt arranger appears not to have been used is the one substantive criticism the episode carries: the film look arrived before the stunt work to fill it.

What the episode does best is the premise itself. It does not explain the second operation early and it does not tidy the coincidence, and the danger being internal to the police rather than criminal is a device the series uses elsewhere but rarely as centrally. The other strand worth noting is the romantic one, played straight. Bulman, the wrong side of fifty, gloved and given to quoting what he has been reading, becomes interested in Dr Anne Kristen's Dr Helen Slater after an accident on the quay, and Henderson plays the attraction without making the character ridiculous. It is contained to this story and she does not return, which is the right decision.

Doran's recognition by a gang member is a professional hazard specific to her character rather than a generic complication, and it is one of her last pieces of substantial work before she leaves. She has two more episodes to run; Bennett arrives at episode four. Rainbow is at his clearest here before being withdrawn at the end of the series.