The Asian kid was rifling through her bag, looking for her purse whilst his fat friend grabbed her arm, trying to pull off her watch. Her eyes were locked open in terror.

Ben stepped out of the shadows. They froze. Stared at him. Lucy gasped his name.

His mind was full of the ways he could take them out. Three seconds, and they could all be down and broken on the ground. As for the knife, it was big and scary to the average victim, but the leader kid had no idea how to use it. Not against someone trained to take it off him and drive it into his brain pan before he could even draw a breath.

They were dangerous kids. But still kids.

‘Open the purse,’ he said to the Asian one. The kid glanced down at it, then back at Ben. He blinked.

‘Go on, open it,’ Ben said, keeping his eyes on the leader. His voice was steady and soft.

The knife kid was frowning and Ben could see the confusion in his face. He knew what he was thinking. Three against one, but something was horribly wrong with the balance of power. His confidence was ebbing away fast, and the defiance in his eyes was fading into fear as he fought for words. The knife was wavering a little in his fist. He slackened his hold on Lucy, and she wriggled away from him.

The Asian kid did what he was told. The purse was tan leather, well worn. He unsnapped the catch and opened it.

‘How much cash is in there?’ Ben asked.

The kid dipped his fingers inside the purse and came out with a twenty.

‘Not much of a haul, boys,’ Ben said. ‘Less than seven pounds each. Then you’d find that the debit card’s no good because the account is already in the red. And the credit card is maxed out. Let’s face it, she doesn’t have the money. So you go home with seven pounds. Real hard guys. A great night’s work, something you can go and boast about to your friends.’

The kid with the knife finally found his voice again. ‘Fuck you,’ he said. But he couldn’t hide the quaver in his throat.

Ben ignored him. ‘OK, let’s make a deal here.’ He reached into the back pocket of his jeans. Took out his wallet and flipped it open. Inside it was a sheaf of fifties, crisp from the cash machine. He counted through them slowly, taking his time, feeling their eyes on him. He picked out six notes and tucked the wallet back in his jeans. ‘Three hundred. A hundred each. Better than seven. And much more than you’re worth.’ He held it out to them. ‘It’s yours.’

The knife guy stepped forward to take it.

Ben pulled the money back. ‘This is a trade. That means I want something from you in return. Four things. One, let her go free. Two, give her back her bag. Three, put the knife on the ground. Then I’ll give you the money. Nice and easy. Four, then you leave, and I don’t ever want to see you again.’

They hesitated.

‘If you don’t want to trade, that’s OK too,’ Ben said. ‘The only thing is, you’ll all be dead within the next half-minute because I can’t think of any other options. It’s up to you.’

The Asian kid was beginning to tremble violently. The knife kid’s eyes were bulging wide. Nervous glances passed between them all.

‘I’m offering you a way out here,’ Ben said. ‘I’m buying your lives back from you, so that I don’t have to kill you.’

The leader stooped and laid down the knife. The blade clinked against the cobbles. The Asian kid handed the bag back to Lucy, and then they all moved quickly away from her. She was shaking, pale. She scurried over to Ben’s side, and he laid a hand on her shoulder.

He kicked the knife away across the alley. ‘Good choice. A defining moment. You’ve no idea how lucky you were tonight.’ He held the money out. The leader kid’s fingers were trembling as he went to take it. Then all three of them turned tail and ran like hell.

‘Are you all right?’ Ben asked Lucy.

She looked up at him. Her eyes were wet in the darkness. ‘I can’t believe what you just did. How did you do that?’

‘Let me walk you home,’ he said.

The seventh day

The Bradburys lived in a large Victorian semi-detached house on the edge of the leafy suburb of Summertown. Ben arrived at twelve thirty with a bottle of wine and some flowers for Jane Bradbury. He hadn’t seen her in a very long time. Physically, she’d changed little, other than some grey streaks in her dark hair – and he thought he could see a certain fragility in her thin frame that hadn’t been there before. He remembered her as a quiet woman, slightly in the shadow of her ebullient husband. But today she was even quieter than he recalled.

Lunch was served on the patio at the rear of the house. The garden hadn’t changed much in almost two decades. Tom Bradbury’s rose bushes were even bigger and more colourful than Ben remembered, and the high stone walls around the edge of the garden were now covered in ivy.

After lunch they sat and sipped wine and made small talk for a while while the Bradburys’ Westie, a sturdy little white terrier, all muscle and hair, ran to and fro across the lawn, sniffing through the grass on the trail of something. ‘That dog looks exactly like the one you had last time I was here,’ Ben said. ‘Surely it can’t be the same one?’

‘That was Sherry you remember,’ Jane Bradbury said. ‘This is Whisky. Sherry’s son.’

Hearing his name mentioned, the dog stopped what he was doing and came running. He trotted up to Ben, sat back on his haunches and offered his paw.

‘Our daughter Zoë taught him that,’ Bradbury said. ‘He’s really more her dog. But we look after him most of the time, since she’s not here very often.’

‘How is Zoë?’ Ben asked.

It was just a casual question, but it seemed to have a strange effect. Bradbury shifted uncomfortably in his seat and looked down at his hands. His wife paled noticeably. Her face tightened and her movements stiffened. She caught her husband’s eye, her look full of meaning, as if she was urging him to say something.

‘Is anything wrong?’ Ben asked.

Bradbury patted his wife’s hand. She sat back in her chair. The professor turned to Ben. He seemed about to speak, then instead reached across the table for the bottle and topped up all three glasses. He set the bottle down, picked up his glass and gulped half of it back.

‘I’m getting the impression this isn’t just a social occasion,’ Ben said. ‘You want to talk to me about something.’

Bradbury dabbed the corners of his mouth with a napkin. His wife stood up nervously. ‘I’ll fetch more wine.’

Bradbury reached into the hip pocket of his tweed jacket, brought out the old briar pipe and started packing the bowl with tobacco from a plastic pouch.

Ben waited patiently for him to speak.

Bradbury was frowning as he lit the pipe. ‘We’re happy to see you again,’ he said through a cloud of aromatic smoke. ‘Jane and I would have invited you here to have lunch with us, even in normal circumstances.’

‘So you’ve asked me here for a particular reason,’ Ben said. ‘Something’s wrong.’

Jane Bradbury came back out of the house carrying another wine bottle, which she placed on the table. It looked from their faces as though they had a lot to tell Ben, and it was going to be a long afternoon.

The professor and his wife exchanged glances. ‘I know it’s been a long time since we were in touch,’ Bradbury said. ‘But your father and I were good friends. Close friends. And we think of you as a friend too.’

‘I appreciate that,’ Ben said.

‘So we feel we can trust you,’ Bradbury went on. ‘And confide in you.’

‘Of course.’ Ben leaned forward in his chair.

‘We need your help.’ Bradbury hesitated, then continued. ‘It’s like this. When you left Oxford, all those years ago, we heard rumours. That you had drifted for a while, and then joined the army. Apparently done very well there. Just rumours, nothing specific. Then, six weeks ago, when we interviewed you as a returning mature student, you told me and my colleagues a little about the career you had pursued in the meantime. I know you didn’t want to go into too much detail. But you said enough to give me a clear impression. I understand you’re a man with a very specific set of skills and a great deal of experience. You look for lost people.’