The Oblong Murders

Barnaby sends DS Ben Jones undercover into a New Age cult. A young woman walked into the group's introduction course and never came back out, and the only way to find out why is from the inside. Jones draws the short straw, and there's quiet fun in watching a policeman try to pass as a seeker.

Undercover means sitting through the group's classes and its polite communal evenings, one eye on the teachings and one on whoever might know what happened to the missing woman. It's slow, watchful work. And the longer Jones stays, the harder it gets to tell genuine belief from something nastier. The questions are the ones Barnaby would ask from his desk: who stood to gain from the disappearance, and how deep did the community's secrets go. Barnaby's instinct is that nobody vanishes from a group like this without someone inside knowing, and Jones has to find that someone without getting rumbled first.

Neil Dudgeon's Barnaby runs the case from a sensible distance while Jason Hughes's Jones does the uncomfortable middle of it. Barry Jackson's Dr Bullard is on hand, and Fiona Dolman's Sarah Barnaby keeps the home front ticking. The cult comes to life through a strong supporting cast: Will Knightley's Max Fuller, Richard Albrecht and Heather Tobias as Mr and Mrs Oliver, John Woodvine's Commodore, Kevin Doyle's Paddy Powell and Holly Aird's Claire Powell. David Hoskins and Caroline Graham wrote it, Renny Rye directed.

This one is more mood piece than puzzle-box, and all the better for it. The answers, when they come, are a lot more ordinary than the surroundings promised, which is rather the point. Whatever language the group wrapped itself in, the case resolves into human motives. Jones gets out with the job done and the village gets its quiet back. Good, uneasy television.