Bright Constable Twitten (Matt Green) wants to cheer up poor Sergeant Brunswick (John Ramm) but it's hard going when they're under the command of Inspector Steine (pronounced Steen and played by Michael Fenton Stevens) who can't spot a crime when it's going on in his own nick. As it often is, as their cleaning lady Mrs Groynes (Samantha Spiro) is a criminal mastermind. Enter Harry Jupiter (Philip Jackson), top reporter and Brunswick's idol. You have to be spry to follow the twists in Lynne Truss's cartwheeling comedy.

Lynne Truss's sublime Brighton-set police drama pastiche returns for a six-part run. It's still 1957 and Sgt Brunswick remains the worst undercover operative around, regularly getting shot for his troubles. Yet he's attracted the attention of a tenacious crime reporter who wants to write about the ordinary heroic copper. But what will the Daily Clarion's finest make of an officer with 36 bullet-hole scars who thinks the idea of a criminal records system sounds like "girls' work"? As usual, the period detail and post-war patter impresses, but the whole thing is stolen by cockney-charlady-cum-crooked-mastermind Mrs Groynes (Samantha Spiro) who effortlessly shoehorns in such berserk but perspicacious declarations as, "well all this standing around jawing won't get the Rome Treaty ratified and change the course of European affairs irrevocably and for ever now, will it dears?"

The Casebook of Inspector Steine, penned and undoubtedly immaculately punctuated by Lynne Truss, oozes period atmosphere. Like everything in this classy comedy-drama, the atmospherics are done mostly for laughs - and so the sound effects are ticklishly overdone - but also to convey 1950s Brighton in its raffish glory.

Truss draws a world whose first aim is to make you smile, but it's a dramatic world you can lose yourself in.

At the heart of Truss's drama are the likable staples of a hapless, high-ranked detective, in Steine, and the rich seam that is surface appearance versus a grimy underbelly. Nothing, apart from Steine's worryingly detached air - I hope you remembered the humbugs, Brunswick is about as focused as he gets - is what it seems. For six months, Brighton is crime-free, and the local constabulary is delighted rather than puzzled. Steine works on his golf handicap, while a constable knocks out a ground-breaking sociological study of kinship patterns in the Fens.

The return of the cops'n'comedy capers set in Brighton during the 1950s, written by Lynne Truss. When we rejoin the action, crime has ceased on the South Coast; nothing for months while the rest of the country is up to its winkle-pickers and drape jackets in juvenile delinquency. This is because Twitten (Matt Green) the fiercely bright constable, has forced Mrs Groyne (Samantha Spiro) the police station char and secret criminal mastermind, out of business by threatening to reveal her crimes in a letter he has deposited with his solicitor unless she cuts out the criminality.

And so the coppers languish; Twitten works on his book; Inspector Steine (Michael Fenton Stevens), Brighton's answer to Jacques Clouseau, works on his golf; Sergeant Brunswick (John Ramm) infiltrates a string quartet he suspects of being a band of brigands.

It's all engagingly silly, crammed with period detail jammed into the narrative: Well, standing around talking won't get worldwide success for Colin Wilson's unreadable novel The Outsider, says Mrs Groyne, who is much given to such gnomic utterances.

Lynne Truss's answer to Inspector Clouseau is a 1950s Brighton cop who believes he has cleaned up all the crime on his patch. Little does Inspector Steine (Michael Fenton Stevens) realise that the station charlady, Mrs Groynes (Sam Spiro) is a criminal mastermind. Fortunately for the next five weeks, PC Twitten (Matt Green) is on her case and doughty Sergeant Brunswick (John Ramm) is there to clear up the loose ends, even when, as today, they festoon the Hippodrome.

When the Brighton police discover a torso in a trunk, Sergeant Brunswick knows what to do: he'll go undercover in the left-luggage office and see if an 'at box turns up[q].

Lynne Truss's radio comedy series, set in a pastiche of the 1950s, has many such gloriously absurd moments, as an inept trio of coppers let the criminal gangs of the Sussex seaside town run rings round them. The dialogue is pure postwar: some authentic, some recognisable from the films and 'wireless' programmes of the time and some cheerful inventions: or maybe people back then really did say [q]he's one cha short of a cha cha cha. You can smell and taste the 1950s, too, with the food - pink blancmange, rock salmon and chips, garibaldi biscuits and the knickerbocker glory. Delicious fun.