‘He’s probably in our bedroom,’ said Tracy as they looked inside the empty room, with its untouched bed. ‘Maybe he’s just gone to sleep.’

‘Maybe,’ said Nick.

‘Maybe we’re just being stupid,’ continued Tracy with a laugh so false it hurt to hear it. Her voice was cracking. ‘We’re going to giggle about this in the morning.’

‘What’s that on the bed covers?’ Ash pointed to a couple of spots of red on the far side of the bed that stood out on the white duvet cover.

A faint gurgling sound came from somewhere in the room, out of sight. Almost a choke but not quite. A human sound.

No one moved. No one said a word. Because they all knew that it came from Guy.

The knife flew out from behind the door, like a snake striking, attached to a gloved hand. It buried itself in Nick’s gut.

Tracy screamed. Ash simply watched, caught in slow motion as her husband made a sound like a hiccup, his eyes widening.

The knife was suddenly withdrawn and a figure in black filled up the doorway. He drove the blade into Nick a second time, then shoved him backwards, like he was some kind of annoying shop dummy, sending him crashing over the banister and down the wooden steps.

For a long, terrible second Ash was frozen to the spot, just like she had been during the mugging. The shocking nature of what was happening was too much to take in. Her husband, the man she’d spent almost a third of her life with, her soulmate, her whole life for God’s sake, had just been murdered in front of her. He was gone. Just like that.

And she was next.

The killer was big and powerful-looking, with a black hood covering his features. And he was fast. Very fast. He swung round to face her, ready to deal her a blow with the bloodied knife.

It was at this point that Ash finally realised she had to move fast. In one movement she turned and ran, but careered straight into Tracy, who hadn’t yet got out of the way, and who was still screaming.

Ash stumbled, losing her balance, and fell forward, letting go of the knife in the process. Out of the corner of her eye she saw Tracy, who was still on her feet, dash for the stairs. Then Ash was rolling round to face her husband’s killer, at the same time scrabbling about for the knife.

A drop of Nick’s blood fell from the killer’s knife blade, splashing her face with a disgusting warmth as he loomed over her. He grabbed Ash by one wrist and yanked her roughly to her feet.

Operating entirely on instinct, she threw a wild punch, catching him full in the face before he had a chance to drive the knife into her. Ash kept fit. She worked out three times a week and had recently started doing boxercise. She thanked God for all these things now because the punch was a good one. It knocked him into the banister and made him loosen his grip on Ash’s wrist.

Pulling free, she turned and ran, following Tracy.

But Tracy had stopped at the top of the stairs and was looking down them with an expression of pure terror. ‘There’s another one coming!’ she screamed. ‘He’s got in the front door!’

Ash didn’t even have time to look, let alone take in the fact that there were possibly two of these psychopaths rather than one, and that the other had come through a door that she knew was locked. She didn’t even look back towards her husband, because there was no time for that. Her survival instinct had kicked in. She sprinted the length of the landing, towards the door to the bedroom she and Nick should have been sharing that night, yelling at Tracy to come with her.

Ash hit the door at a run, flinging it open without even giving a thought to who might be behind it. She could hear Tracy right behind her and she hauled her in. As the dark figure of the killer moved towards them she slammed the door shut, noticing with huge relief that there was a key in the lock. Pressing her whole body against the door, she turned it with shaking hands. She could hear him outside, his breathing calm and steady, as he tried and failed to turn the handle.

A split second later the door shook on its hinges as he slammed into it from the other side. It was only a small lock and she knew it wasn’t going to hold for more than a few seconds.

They were trapped.

The door shook again, and this time she heard the sound of wood splitting.

Looking round desperately, Ash spotted the sash window. It was the only way out. Vaulting the bed, she dashed over and flicked the catch on the lower window, yanking it upwards as hard as she could. The drop to the patio below was a good fifteen feet, but they had no choice.

‘Come on!’ she screamed at Tracy, who was still staring at the door. ‘Move it!’

Tracy ran over, took one look through the window, and turned to Ash. She started to say something, but Ash wasn’t listening. As the door shook once again, almost giving way this time, she grabbed Tracy by the collar and pushed her into the gap. ‘Go! Go! Go!’ she screamed, clambering out after her.

Tracy jumped, letting out a long shriek, at just the moment when the door flew open and the killer came striding into the room. He made straight for Ash with the bloodied knife raised, like something out of one of those horror films that had always scared her as a teenager.

Ash threw her legs out of the window and slid through it, grabbing at the window ledge with both hands as she swung round, hoping to lessen the distance between herself and the ground before she jumped. But as she let go a gloved hand grabbed her wrist. Suddenly she was dangling helplessly in mid-air. The killer began to lift her back up with an almost unbelievable strength, while bringing his knife hand down in the direction of her throat.

Knowing she had just seconds left, Ash pulled and struggled with all her might, wriggling like a fish on the line, and the next second she was falling through the air.

Ash hit the tarmac feet first and a stinging pain shot up her legs. She rolled over and leaped to her feet. Tracy was already staggering towards the trees a few yards away. Ash caught her up and grabbed her by the arm, dragging her along as she tried to put as much distance between them and the house as possible.

‘I’m hurt,’ whined Tracy, slowing down. ‘I think I’ve broken my ankle.’

‘I don’t care!’ hissed Ash, staring her right in the eye as they fought their way into the forest. ‘Run on it. You’ve got no choice.’

For a long moment, Ash thought about leaving Tracy behind, knowing she’d be far quicker on her own. But she stopped herself, because she knew she’d never be able to live with the guilt if she bolted now.

She took a quick glance over her shoulder and thought she saw a figure moving just inside the trees. It spurred her into running even faster. This time Tracy kept up, although she was limping badly and her face was taut with pain. What was truly terrifying Ash was the fact that these men, whoever they were, hadn’t uttered a single word. They were going about their murderous work as if it was the most natural thing in the world.

Ash had no idea why the four of them were being targeted. It had to be something to do with the girl, but she wasn’t even with them now, so why were they still coming? Whatever the reason, Ash had an awful feeling that they weren’t going to stop until she and Tracy were dead.

They were tearing through the branches now, ignoring the bushes and brambles that slashed at them, concentrating everything on escape. These were big woods. There would be plenty of places to hide. They could find somewhere, then wait for morning and raise the alarm.

Ash felt the first stirrings of hope. They were moving fast and there were no sounds of pursuit. Tracy was in pain, but adrenalin and fear were driving them both on, deeper and deeper into the forest.

Then her friend let out a terrible scream and Ash’s hope vanished.