The vampire smiled at Angela, who gave him a wide smile in return, then stepped forward and spat in his face.

Oh shit, thought Matt, and looked desperately at the Director. Turner was watching with his usual impassive expression, but his hand had gone to the grip of his T-Bone.

A deep growl rumbled from the vampire’s throat. Slowly – dreadfully, ominously slowly – he raised his hand and wiped the spit from his cheek, his eyes locked on Angela as red flickered in their corners.

“Valentin,” said Turner, his voice low and full of warning.

The vampire and the Security Officer stared at each other for a seemingly endless moment, pregnant with the prospect of disaster. Then, with a casualness that was either genuine or a truly phenomenal piece of acting, Valentin broke their gaze and smiled at Matt.

“Next,” he said.

A doctor appeared at Angela’s side, pressed a bandage to her neck, and led her towards one of the beds. She looked back over her shoulder as she went, her eyes full of anger, until a curtain was drawn round the bed at the furthest end of the room, hiding her from view.

The second Operator in line stepped forward, a man in his early forties whom Matt didn’t recognise. His face was ghostly pale, but his hands were steady as he unzipped his uniform and turned his head.

“Don’t be ridiculous,” said Valentin, smiling at the man. “Roll your sleeve up, for heaven’s sake.”

The man frowned, but did as he was told. Valentin raised the Operator’s arm, gave the skin of the wrist the tiniest bite imaginable, and let him go.

“Next,” said the vampire.

Pete Randall put his car into gear and followed Greg Browning through the dark streets of Lincoln, keeping a safe distance between them.

He had tried to persuade himself that everything was fine, for mostly personal reasons; he was tired, and he wanted more than anything to believe in what they were doing at SSL, that it really was the force for good that Greg had pitched to him.

But he could no longer convince himself. His friend’s behaviour following the announcement of the cure had been the final straw, the tipping point for concerns that had been growing steadily for some time, not least the unsettling coincidences he had found in the call logs, the incident with the security guard at the blood drive in Peterborough, and Greg’s blatant lies afterwards.

Pete hoped there was nothing going on. He really, truly did. Nothing would give him greater pleasure than to have to admit to himself that he was simply a paranoid fool who had clearly lost the ability to trust people.

He just wasn’t sure that was the case.

Two hundred metres ahead, Greg turned left at an intersection; he was strolling along, his hands in his pockets, headphones in his ears, his eyes fixed forward. Pete pulled over, counted thirty seconds in his head, then followed his friend round the corner.

Greg was gone.

The road stretching out in front of Pete was long and straight, but there was no sign of his friend on either pavement.

Lost him, he told himself. Lost him after barely two minutes. What a bloody awful spy you’d have made.

He slowed the car to a crawl, peering desperately out of the windows on both sides. As he passed a newsagent’s, the shop door opened and Greg emerged, his attention focused on the chocolate bar he was unwrapping. Pete froze behind the wheel; there were less than ten metres between them, and if Greg looked up, they would be staring straight at each other. He fought back the urge to stamp his foot on to the accelerator; a revving engine and squeal of tyres would be guaranteed to draw his friend’s attention. Instead, Pete forced himself to maintain his speed, hoping that a nondescript car passing by on a main road would not qualify as noteworthy. His heart thumped as he rolled forward, his eyes locked on the rear-view mirror, through which he could see Greg stuffing chocolate into his mouth as he resumed his stroll. Pete took the first left he came to, accelerated, took two more lefts, and turned back on to the main road, a safe distance behind his friend again.

He kept up his slow surveillance for the next fifteen minutes, during which his friend did nothing to suggest he was doing anything other than enjoying a walk in the cool evening air. As the shops and commercial buildings began to give way to suburban streets, Greg finally turned off the main road, and walked across the forecourt of a pub called The Red Lion.

What a waste of time this has been, thought Pete. He’s going for a bloody drink after work.

But as he parked his car down the quiet street at the side of the pub, a question occurred to him.

Who with? Greg spends more time than anyone in the office, and he’s never mentioned any friends in Lincoln. So unless he’s come three miles away from his flat to have a drink on his own, who’s he meeting in there?

Barely fifteen minutes later he got his answer.

Greg emerged from the pub at the centre of a group of men, laughing and jostling and pushing each other like teenagers on a night out. Pete watched them carefully, waiting for them to pass beneath the street light outside the pub, and drew in a sharp breath when they did.

There were eight of them, including Greg. He didn’t recognise three of them, although he instantly didn’t like the look of them; they looked like hard men, their heads shaved, their jaws square, their bodies thickly muscled. The other four he knew; three were SSL volunteers, all of them men in their twenties who had joined in the past month, as the charity had expanded as fast as it could. The final man, who was walking beside Greg and chatting to him like they were old friends, was Phil Baker, the security guard Pete had dismissed from the blood drive in Peterborough.

I knew there was something going on, he thought. I bloody knew it.

The men turned on to the road where Pete was parked, and a burst of panic raced through him. They were still fifty metres away, but were walking directly towards him; he didn’t know whether Greg would recognise his car, but he was absolutely certain that he would recognise his friend sitting behind the wheel. He huddled low in his seat, ready to duck down and squeeze himself into the footwell, his eyes peering over the black plastic of the dashboard, his heart pounding.

Barely thirty metres away, Greg stopped and unlocked a car that Pete had never seen before. Baker opened the doors of a jeep parked behind it, and the eight men folded themselves into the two vehicles; it looked like a tight squeeze, even from Pete’s unorthodox vantage point. He watched as the two vehicles pulled away from the kerb, and sat up in his seat as the tension in his chest eased. He started his car, waited thirty seconds, then followed them back out on to the main road.

Twenty minutes later, Pete pulled to a halt behind a low-lying sprawl of industrial units on the outskirts of Lincoln.

The vehicles he was following had stopped outside a warehouse at the end of the road while one of the men got out and rolled up a wide metal door, then disappeared inside the building. Pete got out of his car, made his way slowly down the side street until he reached the corner, and peered round it.

The rolling door was still raised, and he could hear the noise of engines. He squinted into the dark warehouse, desperate to know what was going on, then shrank back as headlights blazed into life, seeming to point directly at him. He pressed himself against the wall, crept forward again, and looked back round the corner in time to see four black vans drive out of the warehouse and on to the road, one after the other. Three immediately accelerated away while the fourth stopped by the open warehouse door, its engine rumbling. Pete shielded his eyes against the glare of the headlights and saw Greg hop down from the driver’s side. He lowered the metal door, locked it, and walked back to the van.