It seemed as if the dog didn’t belong to anyone but then a man lumbered up, bearing down on the dog, barking orders at it, ‘YoufuckinglittleshityoucomewhenIcallyou!’ He was a big guy, with a mean expression on his face, barrel-chested like a Rottweiler. Add to that the shaved head, the weight-lifting muscles and a St George’s flag tattooed on his left bicep, twinned with a half-naked woman inked into his right forearm, and, voilà, the perfect English gentleman.

The dog was wearing a collar but instead of a lead the man was carrying a rope, thin like a washing-line, with a noose at one end and without warning he grabbed the dog by the scruff and lassoed it. Then he hitched the dog up in the air so that it started to choke, its small legs paddling helplessly. Just as suddenly the dog was dropped to the ground and the man aimed a kick that connected with the dog’s delicate-looking haunch. The dog cringed and started to tremble in a way that made his heart go out to it. The man yanked on the rope leash and pulled the dog along, shouting, ‘Going to put you down, should have done it the minute that bitch left.’ Dogs and mad Englishmen out in the midday sun.

A commotion was growing quickly, agitated people protesting loudly at the man’s behaviour, a jumble and hum of angry-sounding words – innocent creature – pick on someone your own size – watch it, mate. Mobile phones came out and people started to photograph the man. He took out his own iPhone. He had resisted the temptations of the Apple for a long time but now he had fallen. It was a lovely bit of kit. Until he was eight years old when his family bought a secondhand television that looked as if it was transmitting from Mars, they had only the radio for entertainment and information. In the half-century of his life, a tick on the Doomsday clock, he had borne witness to the most unbelievable technological advances. He had started off listening to an old Bush valve radio in the corner of the living room and now he had a phone in his hand on which he could pretend to throw a scrunched-up piece of paper into a waste bin. The world had waited a long time for that.

He shot off a couple of pictures of the man hitting the dog. Photographic evidence, you never knew when you were going to need it.

A woman’s voice rose shrilly above the others, ‘I’m calling the police,’ and the man snarled, ‘Mind your own fucking business,’ and he continued to drag the dog along the path. He was pulling it so fast that a couple of times it tumbled head over heels and scraped and bounced along the hard surface of the path.

Cruel and unusual punishment, he thought. He had been around violence in one form or another all his life, not always on the receiving end of it, but you had to draw the line somewhere. A small, helpless dog seemed like a good place to draw that line.

He followed the man out of the park. The man’s car was parked nearby and he opened the boot and plucked up the dog and flung it inside where it cowered, shivering and whimpering.

‘You just wait, you little bastard,’ the man said. He already had his mobile phone open, holding it to one ear as he raised a warning finger to the dog in case it made a move to escape. ‘Hey, babe, it’s Colin,’ he said, his voice turning oily, a cage-fighting Romeo.

He frowned, imagining what would happen to the dog when the man got it home. Colin. It seemed unlikely it would be good. He stepped forward, tapped ‘Colin’ on the shoulder, said, ‘Excuse me?’ When Testosterone Man turned round, he said, ‘On guard.’

‘What the fuck are you talking about?’ Colin said and he said, ‘I’m being ironic,’ and delivered a vicious and satisfying uppercut to Colin’s diaphragm. Now that he was no longer subject to institutional rules governing brutality he felt free to hit people at will. He might have been around violence all his life but it was only recently that he was beginning to see the point of it. It used to be that his bark was worse than his bite, now it was the other way round.

His philosophy where fighting was concerned was to keep clear of anything fancy. One good, well-placed blow was usually enough to lay a man down. The punch was driven by a flash of black anger. There were days when he knew who he was. He was his father’s son.

Right enough, Colin’s legs went from beneath him and he dropped to the ground, making a face like a suffocating fish. Strange squeaking and squealing noises came from his lungs as he fought for breath.

He squatted down next to Colin and said, ‘Do that to anyone or anything again – man, woman, child, dog, even a fucking tree – and you’re dead. And you’ll never know whether or not I’m watching you. Understand?’ The man nodded in acknowledgement even though he still hadn’t managed to take a breath, looked in fact like he might never take another one. Bullies were always cowards at heart. His phone had clattered to the pavement and he could hear a woman’s voice saying, ‘Colin? Col – are you still there?’

He stood up and stepped on the phone and ground it into the pavement. Unnecessary and ridiculous but somehow satisfying.

The dog was still cowering in the boot. He could hardly leave it there so he picked it up and was surprised to find that it was warm even though it was shivering all over as if it was frozen. He cradled it against his chest and stroked its head in an effort to reassure it that he wasn’t another big man about to beat it up.

He walked away, the dog still in his arms, glancing back once to make sure that Colin was still alive. It wouldn’t have bothered him too much if he was dead but he didn’t want to find himself on a murder charge.

He could feel the dog’s frightened little heartbeat, a pulse, against his chest. Tic-tic-tic. ‘It’s OK,’ he said, using the tone of voice he had used to soothe his own daughter when she was small. ‘Everything’s OK now.’ It was a long time since he had spoken to a dog. He tried to loosen the rope around the dog’s neck but the knot was too tight. He turned round the tag on the dog’s collar so that he could read it. ‘Let’s see if you’ve got a name,’ he said.

‘The Ambassador?’ Jackson said, looking doubtfully at the small dog. ‘What kind of a name is that?’

He was drifting, a tourist in his own country, not so much a holiday as an exploration. A holiday was lying on a warm beach in a peaceful country with a woman by your side. Jackson had tended to take his women wherever he found them. He didn’t usually go looking.

He had been living in London for the last couple of years, taking over the rent on the little Covent Garden flat in which he had briefly shared a counterfeit marital bliss with his fake wife, Tessa. A man called Andrew Decker had killed himself (somewhat messily) in the living room of the flat and Jackson was surprised how little this bothered him. A specialist trauma-scene cleaning company had come in (now there was a profession you wouldn’t want) and by the time Jackson had changed the carpet and disposed of the chair that Andrew Decker had shot himself in you would never have known that anything untoward had happened. It had been a righteous death and Jackson supposed that made a difference.

Jackson’s official identity was all in the past – army, police, gumshoe. He had been ‘retired’ for a while but that had made him feel as if he was redundant to the world’s needs. Now he called himself ‘semi-retired’ because it was a term that covered a lot of bases, not all of them strictly legal. He was off the grid a lot these days, picking up work here and there. His specialist subject on Mastermind would be looking for people. Not necessarily finding them, but half the equation was better than none. ‘Really you’re looking for your sister,’ Julia said. ‘Your own dear grail. You’re never going to find her, Jackson. She’s gone. She’s never coming back.’

‘I know that.’ Didn’t make any difference, he would go on looking for all the lost girls, the Olivias, the Joannas, the Lauras. And his sister, Niamh, the first lost girl (the last lost girl). Even though he knew exactly where Niamh was, thirty miles away from where he was at the moment, mouldering in cold, damp clay.