It was just gone seven-thirty when Clare’s door opened and she stepped outside. She walked briskly, her head down and her arms, clad in a heavy brown coat, wrapped around her body. She looked small. Sam pulled his hood up and started following from a distance. He only increased his pace once they had both turned on to the main road. Clare didn’t dawdle. She wove in and out of the other pedestrians in the half light; Sam had to concentrate so as not to lose her. She came to a halt at a bus stop where a small crowd had congregated. Sam loitered for a few metres behind, keeping well out of sight.

The bus arrived, a long one with a flexible midriff. It was almost full and the windows were steamed up. Sam joined the queue, a couple of places behind Clare; when the moment came to pay his fare he had to scrabble around in his pocket to find change for the impatient driver. By the time he had paid, Clare had taken a seat towards the back. There was a spare place next to it. He put his head down again and approached her.

She was lost in thought, her pale eyes staring through the window, the condensation on which she had wiped away with one hand. She clearly hadn’t noticed Sam; he waited for the doors to close and the bus to move off before speaking.

‘Clare,’ he said softly. ‘It’s me.’

He felt her body jump and put a reassuring hand on her arm. Never had he seen such alarm in someone’s face. Her skin, already limpid, went white; her eyes bulged.

‘Sam!’

She looked around, as though expecting to see someone else there, but then dragged her attention back to him. She looked frightened now. ‘I had to tell them,’ she whispered. ‘I’m sorry. They threatened me…’

In front of them a drunk started to sing. Most of the other passengers looked at their boots.

‘Forget about it,’ Sam muttered. ‘Look, I need your help.’ He frowned. ‘I didn’t know where else to go.’

She shook her head nervously. ‘I can’t, Sam. I can’t have anything more to do with this.’

One of the passengers in front – an old woman with a hard, nosy face – glanced round at them. Clare bowed her head again. ‘I just can’t,’ she repeated.

The bus came to a halt; a few passengers left, others embarked. A harassed woman with two kids jostled towards Sam, staring at him in a way that suggested he give up his seat. He didn’t. They sat in silence.

‘We need to get off,’ Sam said. ‘We can’t talk here.’

‘I can’t talk anywhere.’ Her voice was shaking. ‘You’ve got to leave me alone.’

His hand was still on her arm. He squeezed it. ‘No one’s followed me,’ he reassured her. ‘I took care.’

Clare looked around again. ‘How do you know nobody’s following me?’ she demanded.

He couldn’t answer that. Instead, he stood up and pulled on her arm. There was a little resistance, but she gave way in the end – not through enthusiasm, he realised, but because she knew she didn’t have much choice. They shuffled, arm in arm, to the double doors. Sam could feel her trembling with anxiety.

When the doors opened next, only a couple of people got out. Sam waited, choosing his moment carefully. Only when he heard the hiss of the doors about to close did he move. He tugged Clare sharply – so sharply that she tripped slightly. The closing doors caught his arm, but they made it on to the street and if anybody had been intending to follow them, they wouldn’t be able to now.

The bus drove off just as Clare angrily pulled her arm from Sam’s wrist. ‘What are you playing at?’ she raged.

They were in a busy, suburban street just outside a rough-looking pub. A couple of passers-by glanced at them, clearly thinking they were having some kind of domestic. Clare stomped off, but Sam kept with her. They walked in silence for at least a hundred metres. In the end, though, as he knew it would, Clare’s curiosity got the better of her. She stopped in the middle of the pavement and looked angrily at him.

‘Did you find it? The training camp?’

He nodded.

‘And did you… the red-light runners… did you…?’ She seemed unable to formulate the words ‘kill them’.

‘I found my brother.’ Sam sidestepped the question.

Her lips thinned. ‘Is he okay?’ she asked, a bit calmer now, her Irish lilt a bit softer.

Sam shrugged. ‘He got away, if that’s what you mean.’ He pulled the laptop from under his jacket. ‘He left this. I can’t get into it, but I think it might have some answers. Seeing as you’re looking for some answers too, I thought you might help me with it.’

Clare hesitated. Her eyes narrowed. ‘That bastard came to my flat again, Sam. Just waltzed right in. He knew you’d been to see me. God knows how, but I couldn’t deny it. How did he know, Sam? Was someone watching you that night?’

‘I don’t really know. Look, do you know someone who can help us with this?’ He grinned. ‘Most of my friends would try to open it with an MP5.’

‘A what?’

‘Never mind. Are you going to help me?’

Clare glanced around, as though searching for a way out. But she didn’t run. She looked at him helplessly. ‘My sister,’ she said in a defeated kind of voice. ‘Her son, he’s a kind of… whizzkid. Nerd, actually. Sits in his room all day with the curtains closed. He could probably…’

Her voice trailed off.

‘Where do they live?’ Sam demanded.

‘Not too far from here. We could get a bus.’

‘We’ll get a cab,’ Sam said shortly. ‘Come on.’

It was a scant twenty minutes later that Sam was putting a ten-pound note into the hand of a cabbie. They were in a residential street that was almost indistinguishable from the one where Clare lived. Only once the cab driver had driven away did Clare lead Sam towards one of the houses. It was a gentrified-looking place: two stories and an elegant pathway with black and white tiles in a chequer pattern. Clare turned to him. ‘His name’s Patrick,’ she said. ‘He’s sweet, but he’s a bit of a… a teenager, if you know what I mean. A bit… Just go easy on him, that’s all.’

‘I’ll be good as gold,’ Sam murmured.

Clare led him up the path and rang on the doorbell, while Sam lurked a metre or two behind her.

It took a minute for anyone to answer. When the door opened, a kid stood in the frame. He was thirteen, maybe a bit older – Sam had no talent for judging such things. His hair was lank and he had whiteheads on his forehead and cheeks. Fuck, the kid had a face like a pepperoni pizza. He stank of BO and sly wanks. He was probably in the middle of a crafty hand-shandy when they had arrived. That was probably why he was in such a foul mood. He looked at Clare about as enthusiastically as he might look at a door-to-door salesman.

‘Hi, Patch,’ Clare said brightly.

‘It’s Patrick,’ the teenager replied.

‘Mum in? Dad?’

He shook his head.

‘Mind if we come in?’

Patrick looked over her shoulder at Sam, appearing to measure him up. ‘He your boyfriend?’

An awkward pause. From behind, Sam saw her put her fingers lightly to her hair. ‘This is Sam,’ she replied. ‘Can we come in please, Patrick?’

The kid shrugged and stepped aside.

It was warm in the house. Warm and quiet. The kid shut the door and then loitered uncomfortably in the hallway, too gawky to look directly at his aunt or her guest. ‘Actually, Patrick,’ Clare said, delicately, like she was tiptoeing, ‘it’s you we came to see. We need some help. Sort of a computer thing.’

Patrick did his best to pretend not to be interested.

From under his jacket, Sam pulled the laptop. ‘Forgot the password,’ he said. His voice sounded a bit clumsy in his ears. He wasn’t used to talking with children.

Patrick looked at the laptop, then up at Sam. ‘No one forgets their password,’ he said.

‘Please, Patrick,’ Clare interrupted quickly. ‘It would be a real help. Can you get into it?’

Patrick shrugged again. It looked to Sam like this was a default action for him.