The detective, Tony Clark (Neil Pearson, the leather jacket), and his colleague Maureen Connell (Siobhan Redmond, the redhead) are discussing a case as they go about their business. This may be a cop show, but there isn't a sawn-off shotgun or a handbrake turn in sight.
After the first two runs of BBC1's series about the Metropolitan Police Criminal Investigations Bureau, several Baftas and Royal Television Society Awards were collared. The Independent called it 'the best police drama on TV'; the Daily Telegraph described it as 'a splendid piece of work', and the Sunday Times referred to it as 'a jewel in the BBC schedule'. After the critical calamities of Eldorado, Westbeach, Trainer and Moon and Son (to name but a few), BBC1 at last had a popular drama to be proud of. It passes the acid test: you tape it if you're going out.
But what raises Between the Lines above the routine patrols of other British cop shows? The acting is of the highest order, certainly. The three detectives - Pearson, a heart-throb just the right side of seedy; Tom Georgeson (who plays Harry Naylor), a hard-bitten chainsmoker just the wrong side of seedy; and Redmond, a sparky lesbian with a tendency to tell people to 'Foxtrot Oscar' - are supported by the softly spoken Irish menace of Tony Doyle's Deakin, Clark's corrupt former boss.
The writing and directing are first-class - but that's par for the course with telly 'tecs these days. No, what makes the show unusual is that words speak louder than actions. Most of the series is taken up with talk.
Over a meal of lamb curry in the catering- bus after the floral scene, Pearson reflects on the supremacy of word over deed. 'Our screaming-tyre quotient is very low, but as a result of that, you can hear what the characters are saying, and usually they're saying something worth hearing.'
In many scenes, desk-bound officers plough through acres of paper. It's plodding policework - taped interviews, the reading of rights and playing it by the procedural book, a far cry from the Sweeney-esque cliches of driving round corners on two wheels and being bashed with baseball-bats by escaped cons with names like Mad Harry and Knuckles. Michael Wearing, head of BBC Drama Serials, says that 'the violence in Between the Lines is much more psychological' - before adding: 'Anyway, we can't afford massive car chases under the new rigours of Birt's Year Zero.'
The other Unique Selling Point of Between the Lines is that it is about the police who police the police. As films such as Serpico and Internal Affairs have shown, this is a field fertile with dramatic possibilities. None of the usual strictures about good and evil apply. Just look at the title. 'Rather than good guys chasing bad guys, the conflict between good and evil is played out in the head of one person,' says J C Wilsher, the writer who created the series and is now responsible for 'the bible', the overarching storyline. 'You might show someone who did something bad but not necessarily for bad reasons. We wanted to raise moral problems, not offer solutions.'
Pearson takes up the theme. 'Most cop shows are black hat-white hat. At the end of 50 minutes, all loose ends are tied up, the good guys have won, see you next week. Between the Lines is grey. We caught two people in the whole of the second series - and one of them was the Met's major thief-taker. The fact that people know it may not turn out OK intrigues them. Usually there's the assumption that whatever happens, the baddy is going to get caught and the good guy won't get killed. In this, you can't take anything for granted.'
And that includes a clear, linear plot. Some viewers profess to being baffled even after watching an episode twice, as characters are triple- and quadruple-crossed. Tony Garnett, the executive producer, sees the complexity as an advantage. 'The series is an attempt to make some entertainment for grown-ups. Some people will never want to be grown-up so the audience will be limited (an average of 8 million in the last series). But if there isn't a place for shows like this, then it's a duller world. Our leading characters often don't understand what's going on. They're floundering in a world that's too complicated for them. I have that feeling all the time - don't you?'
Over many distinguished years as a producer, Garnett has established a reputation for socially challenging work: Cathy Come Home, Up the Junction, Kes, Law and Order, and the latest series to have backbench Tory MPs foaming at the mouth, the NHS drama Cardiac Arrest. Garnett had 'had an eye on a police procedural' for some time when Wilsher, a writer on The Bill, came to him with a proposal about a CIB series. 'I knew it was a good idea,' Garnett recalls, 'because I thought, 'why didn't I think of that?'. It also meant I could have bent coppers on every week.'
Between the Lines has more bad apples than a cider factory, but in that it merely mirrors the changing image of the police. After many well- documented miscarriages of justice, says Wearing, 'it would be difficult to pretend that the public perception of the police is still Dixon of Dock Green. Between the Lines reflects that the police have been found fairly wanting. But it also shows how difficult being a police officer is. It's not a completely knocking show; it does graphically reveal the stresses and strains of being at the chalkface of modern society.'
Serving officers certainly didn't see it as an act of GBH on their profession. 'During the first series,' Wilsher says, 'applications to CIB rocketed. It was suddenly perceived as something sexy and glamorous.'
This may well have had something to do with the sexual voracity of the central character, who sometimes seemed more like Alan than Tony Clark. Pearson - who plays the equally jack-the-laddish Dave in Drop the Dead Donkey - wasn't that enamoured with the series's nicknames: Between the Sheets, Between the Loins, Between the Legs. 'After the first series, I said, 'can I keep my trousers on a bit more in the second series, please?'
'The first series was at its least successful when it diverged most from reality, when it became James Bond-y in its serial shagging. 'I'm Tony Clark.' 'Right, well I'll get my kit off then.' Given that we were paying such attention to getting real life right elsewhere, I didn't like that.'
The other area where the series has strained credulity is its jargon. People who have a cast- iron alibi are 'fireproof', lying witnesses are 'painting a picture,' and every boss is 'guv'.
Pearson maintains, however, that 'they really do talk like that. We tone it down - otherwise it becomes Sweeney-speak. Police officers do say things like 'the job's going pear- shaped' and 'can't get the toothpaste back in the tube'. There's this strange symbiosis going on. The way the police have talked on television in the past has infused itself into the way they talk now. We're giving it back.'
The third series returns to its beat on Wednesday. It will present a whole range of new moral dilemmas, as Clark and Naylor are drummed out of the force and become involved in the shadowy world of private security, in thrall to the incandescently sinister Deakin.
Part of the reason for this change, Pearson explains, is that 'there are only so many ways you can shoot a police interview. When you're putting the camera on the ceiling and filming through a slowly turning fan, then you know you're in big trouble. That's the last idea.'
The third series of 'Between the Lines' starts on Wednesday, BBC1, 9.30-10.25pm.