This gothic BBC comedy-thriller written by Reece Shearsmith and Steve Pemberton is as brutal, gory and funny as The League of Gentlemen. But also present is a sense of whimsy, even at times an unexpected tenderness. The story begins with five people receiving a letter that reads, 'I know what you did', and leads to an explosive and tense finale. It's shot through with savage comedy, from one man's preoccupation with the bowels of conjoined twins to the slapstick of a blind man trying to make phonecalls on a Club biscuit. The story is brilliantly told and expertly performed, never more so than in the central, fourth episode which is the most rewarding half-hour of the series, shot to suggest one long take. The on-screen chemistry between the League regulars is a joy to watch and moments like Maureen fluttering her cardy to make like Superman are hard to forget.

In the interviews included in the extras on the DVD, producer Jon Plowman reveals Psychoville was written in six parts but when it became apparent the ending was too expensive, Plowman asked the Beeb to make it as a seven-part show, then asked the writers to request an extra, cheap episode. This is the extraordinary fourth ep and is proof that too little money can be an advantage. On the disc, there's even a fascinating split-screen option showing how it was shot.