Synchronicity

Synchronicity is the last episode of the original configuration and the strangest thing the show attempted, and it earns its place by putting the psychologist's own death in the frame at the same time as a case he cannot explain. Tony Hill is hit on the head by a would-be murderer whom he outmanoeuvres psychologically, and wakes in casualty to be told he has a brain tumour. The doctors say it is a matter of chance whether his symptoms signify something fatal.

An anonymous sniper is then picking off victims in the city streets, and the deaths appear meaningless and motiveless. The killer eludes every investigative effort and seems to be taunting the police. Jordan wants Hill's input, but his theories — quantum physics, chaos, probability — sound wild enough to suggest he is becoming unreliable. As the deaths continue, his behaviour grows more erratic, the city is gripped, and Jordan faces an angry press.

The connection the episode makes is between two forms of arbitrariness. Hill's tumour is a matter of chance; the sniper's choice of victims is presented as equally random. To understand the second, Hill has to accept the first, and the film's argument is that only by surrendering to the laws of probability can he and Jordan catch a killer who is not following any rule he can read. It is a genuine departure from the show's method, and it is the point at which the series' faith in interpretation is most visibly strained.

Whether it works is a matter of taste. The physics framing is heavy and the killer's reasoning is asserted more than dramatised, which is a real problem for a show whose appeal is watching reasoning happen. On the other hand, the episode is the only one in the run where the offence has no psychological motive at all, and the show is clear that this is what makes it unwatchable to Hill rather than merely difficult.

The episode also closes the Norris era. Wikipedia records that Jordan forms a close bond with Hill, that they never achieve the romantic relationship she wants, and that Hill is devastated when she leaves Bradfield abruptly. That departure is reported rather than shown — the fourth series begins with her already gone — and the unresolved ending is the most criticised structural decision of the run.

Hermione Norris's last episode gives her the least to do of her three series, because the drama is Hill's. That is a shame, though the film does give her the series' only scene in which she confronts the press while out of her depth, and she plays it with a competence that makes the shouting match something other than a humiliation.

It drew 7.10 million viewers. As a final statement of the original partnership it is more interesting than it is satisfying: an episode that argues the limits of its own central idea, and then ends without settling the question it raised.