She never saw the people who'd killed the two men so close to her brought to justice. It was possible that not all of them had been. This knowledge had scarred her too, and she'd resigned from the force, hit the rails, and become very depressed. She might never have recovered – at one point, things had genuinely felt that bad – but then she'd met Mike Bolt, who was then working for the National Crime Squad, and he must have seen something in her because he persuaded her to join his team, and to move across with them when the NCS became SOCA.

She appreciated what he'd done for her, and she worked hard at her job to demonstrate this. Sometimes she thought Bolt was attracted to her, occasionally even that this was the reason he'd hired her in the first place, and consequently she tended to keep her distance from him in the workplace. He was a good-looking guy, there was no question about that. Tall, broad-shouldered, with blond hair only just beginning to fleck with grey, and piercing blue eyes that were so striking she'd thought at first (wrongly) that he wore contact lenses. She almost certainly would have gone for him at one time, but things were different for her now. She'd had her fingers burned far too badly, and the experience had made her more cautious. She'd become a loner, someone who kept herself to herself both inside and outside a work environment, and she knew that some of the team resented her for it, putting her manner down to a brusqueness that wasn't there.

She'd been a fun girl once. Had got drunk, got laid, travelled the world. Smoked dope so strong in northern Thailand she'd hallucinated. Swum, awestruck, with dolphins on the Great Barrier Reef. Had a real life. She didn't really have one any more, and there were times – more often than she'd like – when she was filled with an angry regret over the path she'd chosen, and its bitter consequences, wondering how things might have turned out if she'd taken the office job.

But today wasn't one of those times. She was actually feeling good as she walked along Colindale Avenue in the direction of the Underground, the autumn sun warming the back of her neck. She was on her way back to the Glasshouse and had already called ahead and told Bolt about Pat Phelan's alleged debt problems, as well as asking him to check out anything they had on Leon Daroyce.

Bolt had seemed pleased with the lead – which he should have been, because it provided them with a motive for the kidnap – but he'd also sounded under strain, which wasn't like him. Mike Bolt was generally calm and level-headed, the type of guy who was able to withstand pressure. It was one of the reasons she enjoyed working with him. She felt she could trust his leadership.

'Hey lady, how you doin'?'

The words, delivered in a deep baritone with a faux American twang, snapped her straight out of her thoughts. She turned to see a silver Merc pull up beside her. The man addressing her through the open window was a well-built, smooth headed black man in his thirties, wearing shades and an expensive-looking suit.

'I'm not buying, I'm not available, and I'm not interested. So piss off.' She looked away and kept walking, but the car kept pace with her.

Tina didn't take kindly to being accosted in the street by strangers. It happened now and again. This was London, after all. She tended to ignore them, and usually they went away, but it didn't look like this guy was going to. She was a hundred metres from the Tube station now, the irony of the fact that she was only spitting distance from Hendon Police College not lost on her. God knows why this guy was picking on her, but if he decided to jump out of the car and cut up rough, then he'd get a lot more than he bargained for.

She heard the guy chuckle. 'You got some spirit, lady. I like that. A friend of mine would like to speak to you. I hear you might want to speak to him too.'

She stopped, turned his way, saw a white guy with a tight T-shirt and big biceps beyond him in the driver's seat.

'Is that right?' she said. 'And who's your friend?'

'His name's Leon, but to you he's Mr Daroyce.'

Tina cursed to herself. How the hell had he found out about her this fast? Then she thought of that brassy bitch who'd taken her up to McMahon's office, and it came to her. She must have been listening at the door. And there she'd been, saying how careful she always was. Not careful enough, darling.

'Thanks for the offer, but I have a rule never to get into cars with strangers.'

'Does it still count if we know you, Tina Boyd?' The man gave her a predatory smile as he made a great show of emphasizing the pronunciation of those last two words.

The use of her name made Tina feel naked and exposed. 'No, it doesn't,' she answered, beginning to turn away.

'If you don't come now, we might have to come and find you, Tina Boyd.' His voice had hardened now, laced with threat.

She turned back. 'What does your friend want?'

'He just wants to talk.' He shrugged his powerful shoulders. 'That's it. Nothing more. I think he might have some information for you.'

He leaned behind him and opened the back door of the Mercedes for her.

Tina made a quick calculation. If they knew her name, they knew she was a SOCA agent. That meant it was unlikely they were going to risk hurting her. Especially when their car, and possibly even their faces, would already have been picked up somewhere on CCTV. And when it came down to it, there was no reason for them to hurt her anyway. She didn't owe Daroyce money, had in fact never met him, which meant the guy in front of her was almost certainly telling the truth.

Those were the pros. There was only one con, but it was a big one. What if she was wrong?

It was a big decision, but in the end – although she'd never admit it to herself – part of the reason Tina Boyd attracted trouble was that she was always prepared to put herself in situations where encountering it was inevitable. And this was one of them. Taking a long look round so that the people walking up and down the street might remember her face if it came to it, she got inside the Merc and shut the door.

'Let's go then,' she said, lighting a cigarette.

They drove through back streets heading west in the direction of Queensbury. Tina tried to make conversation, knowing how important it was to create a rapport with the black guy, who was clearly the senior of the two. But now she was in the car, both men were worryingly reticent. The white guy said nothing at all, his friend either answering her questions with an uninterested yes and no or ignoring them altogether.

The journey didn't last long, ten minutes at most, before they pulled into a dingy dead-end road lined with brand-new low-rise council flats on one side and a pair of grim-looking tower blocks on the other. The car pulled into a parking space in front of the first of the blocks, next to an overflowing bright orange wheelie bin that seemed to be attracting the flies. A gang of half a dozen kids on mountain bikes were messing about by a rusty climbing frame over to one side.

'Nice place,' said Tina, wrinkling her nose against the smell from the bin as she got out of the car.

'Mr Daroyce likes to stay close to his roots,' answered the black guy as they walked over to the front entrance.

Tina noticed the kids give him respectful looks as he passed, before passing more hostile eyes over her. Jesus, she thought. What is it about me? I might as well be wearing a flashing blue light on my head.

They went up to the tenth floor in a graffiti strewn lift with black smoke stains running down two sides as if someone had tried to set it alight, travelling in silence with only the creaking of the cables for company. Tina was getting more and more nervous. She didn't much like going alone to isolated places with the kind of men your mother warned you about, particularly when she was unarmed and out of contact with her colleagues. She thought about trying to leave but had a strong feeling that they wouldn't let her.