The Moscow Subway Murders

Series 4 opens with the new order inside the Inter City Squad. Bulman has been promoted to Detective Chief Inspector, a jump of two ranks from the detective sergeant of the first three series, and the promotion has moved him off the road and behind a desk. He is expected to supervise rather than to work, and the episode's first movement is his frustration at that: he wants to be on a pavement asking questions, not signing other people's paperwork.

A series of murders is under investigation, and the killings are linked to a Soviet national. The Foreign Office takes an interest, which brings Bill Dugdale back into the story as the squad's intelligence liaison. The Metropolitan Police are joined in the hunt by a visiting Moscow detective, Inspector Pushkin, played by George Pravda, who has come to London to track a man who is a killer in the Soviet Union as well as a suspect here. Pushkin is an eccentric of the same order as Bulman, confident and set in his methods and unhurried about explaining them, and the episode's running joke is the clash between two police cultures that both consider themselves self-evidently correct. Eugene Lipinski, Alan Penn and Jiri Stanislav play the Soviet-linked suspects, Georgina Melville is the British point of contact, and Patricia Maynard appears as Jack Lambie's wife.

The case resolves through the identification of the killer as one of the Soviet-linked men, with the motive lying in his own past rather than in the political explanation that first suggested itself. Pushkin's arrival is what turns him from a suspect into a target, and the two detectives have to work the same quarry from two directions. The contribution that matters is the one the promotion was supposed to have taken away from Bulman: he gets out of the office, reads the case as a set of human relationships rather than a set of nationalities, and finds the ground that makes the killings make sense. By the close the political interest that brought Dugdale in has been served, the squad has the man, and Bulman has confirmed to himself that rank has not made him an administrator.

The pairing with Pravda is the episode's best idea. Pushkin is not a villain and not a buffoon; he is a competent detective from a system with different rules, and Pravda plays him with a deadpan courtesy that makes the culture clash land without either man being made a fool. It also gives Henderson something the series rarely provides, which is an equal, and the episode's central scenes are a two-hander in effect, with Henderson reacting rather than dominating.

The mystery itself is the thinnest element. The murders exist largely to bring the two police cultures together, and the solution is reached because the visiting detective already knows the man's history rather than because the squad closes a gap. The rank change is what the episode is really about, and what separates it from a routine instalment: Bulman is a DCI for the first time, the promotion is treated as a problem rather than a reward, and the resolution has him vindicating himself for the job he was moved away from.

The cold-war material is treated as plumbing rather than as ideology. Nobody lectures the audience about the Soviet Union and Pushkin is a professional rather than a symbol, which is why the frame has not dated. The exact mechanics of the killing pattern and the full shape of the solution are not set out in any accessible listing, and the account here states what the credited characters and the episode's structure support.