'You'll need to watch her. She's only small, she's fifty if she's a day, and she looks as if she couldn't hurt a fly. But Olive knows her tennis and she's bloody good at the net. She'll volley it straight into your privates if you give her half a chance.'

It wasn't the kind of conversation you'd expect in a police staff canteen. (The bureaucrats had tried 'restaurant' and 'dining hall', but neither had caught on at Brunton Police Station.) The talk here normally ranged only from the latest atrocities of the criminal fraternity to the latest inanities of the decision makers in the police service.

But then this speaker wasn't the typical consumer of dubious toad-in-the-hole or bangers and mash. Elaine Brockman was graduate entry to this distinctively scented eating place. She lived what seemed to most of her fellow officers an exotic life outside the station. Her father was a civil servant and her mother was a nursing sister. Both of them had bitterly opposed their daughter's choice of career, though no one who sat with Elaine in the canteen knew anything of that.

The officer she was speaking to could hardly have had a more contrasting life. Nor could he have been more physically different. PC Brockman was small and curvaceous and had dark blonde hair. She also had a surprisingly crisp right uppercut when it was needed. This had recently been used more amongst her over-amorous colleagues than amidst the town's yob fraternity. But Elaine weighed no more than a trim nine stones. She was fair-skinned, blue-eyed and deceptively vulnerable in appearance: the right uppercut had surprised its victims.

No one would have described Detective Sergeant Clyde Northcott as vulnerable. He was very black and very powerful. At six feet three and around fifteen stones of bone and muscle, he was not a man anyone cared to argue with. He had first-hand knowledge of the criminal low life, having been a small-time drug dealer for three months when he was nineteen. His lifestyle and his colour had ensured that he had needed from an early age to be very handy with his fists.

Northcott had even been a suspect in a murder case. DCI Peach, his present boss, had cleared him of that and then unexpectedly recruited him to the police service. Now, six years later, he was Peach's bagman and trusted aide, the member of the team whom Peach always described as his 'hard bastard', which added even more to Northcott's formidable reputation. Whereas PC Brockman crept into the police car park each day in an ageing green Toyota passed on to her by her mother, DS Northcott roared in confidently on a Yamaha 350cc motorcycle.

They made an odd couple, but they enjoyed exchanging their very different experiences of life. It was the third time in ten days that they had sat together at lunchtime. An unlikely pair, and today an unlikely subject of conversation: they were talking about tennis. And in particular about the rather snooty Birch Fields Tennis Club. Elaine was filling Clyde Northcott in on the diminutive middle-aged lady who had been endeavouring to recruit him as one of its members.

Olive Crawshaw was her name and Elaine Brockman knew her well. She had known her since she was ten years old. 'She's a lady it isn't easy to say no to,' she told Northcott.

'I found it easy enough to say it. She just didn't seem to hear me,' said the big man plaintively.

'That's Olive. She doesn't hear what she doesn't want to hear. She wears you down. Then, when you show the slightest sign of weakness, she pounces. Just like she does at the net whe