‘I think something’s troubling you.’

‘You’re wrong.’

‘What about your boyfriend? Is he too scared?’

For a moment Hobbes saw something in her eyes, beyond the anger and indignation: fear. It was held deep, well hidden – but once he’d spotted it, persistent.

‘What’s your friend called?’

‘Why should I tell you?’

‘He’s over there.’ Hobbes nodded towards the park. ‘Isn’t that him?’

The girl turned and followed his direction. A young man was turning slowly in a circle beneath a plane tree. One of the girl’s hands reached up as though to signal to him, but fell again. Hobbes saw the marks on the ends of her fingers, each one darkly covered. But he didn’t say anything about it, not yet, not directly.

‘What’s wrong with him?’ he asked. ‘The usual, is it? Drugs?’

‘You don’t know. You can’t know.’

‘You’d be surprised.’

‘Nothing we do is usual. Nothing!’

It was a simple statement, spoken in total anger, and Hobbes was intrigued by it. He tried a different tack, one worried person to another.

‘I’m looking for someone, a young man.’ He let the words sink in, waiting until she gave him her full attention. Then he continued: ‘His family think he’s run away to your place, to Cromwell House. They’re old friends of mine, and they’re worried sick, they really are. They’ve asked me to help.’ He paused, to allow the half-lie to take hold. ‘They just want to know if he’s all right, that’s all. Nothing more, I swear.’

The young woman stared right at him.

‘Are you Hobbes? Detective Hobbes? Martin’s dad?’

He was taken aback. ‘I am, yes. How is he?’

She didn’t answer, not right away. The fear was more present than ever, and her eyes moved from his. She couldn’t face him.

‘Is he in trouble?’

She bent down to pick up one bag, then the other, but the second slipped from her grip and spilled its contents over the pavement. She made a kind of heaving motion with her upper body, then bent down to retrieve the goods. Hobbes made to help her. She brushed his hands away at first, but then let him. He was surprised at the items he saw: not only the food and drink he was expecting, but a curious mixture of objects – a beaded necklace, a pair of spectacles with no glass in them, a Chinese-style fan, a hairnet, two copies of a history of London’s hidden rivers. He couldn’t quite work out the rationale behind the purchases. He picked up sachets of powdered milk and a box of eggs.

‘One of these is broken.’

She sobbed freely at this, way beyond what such a breakage should entail.

‘What’s wrong?’

Still she wouldn’t look at him. Her hands grabbed at chocolate bars and tinned beans. ‘I can’t talk to you, I can’t! I’m not allowed to.’

‘Because I’m a cop, is that it?’

Her sobs mixed with laughter: she was a mess.

He held one of her wrists and put a little pressure on it, enough to stop her moving and to make her look at him.