Tom waited for the CSI van to arrive and watched it park behind the assortment of police vehicles. Both Amanda and Jack got out, suiting and booting themselves ready for the all-clear to go into the scene. The entrance to the road was now cordoned off according to protocol, though the beauty of this street was that it only ever got foot traffic from the people who lived in the three houses along it. All three occupants of one house were dead, Tom lived in another and the very first one was empty. It had been on the market for a couple of months now; the owners had moved away to Australia.

Tom had accompanied the paramedics upstairs and shown them the three bodies whilst Lucy and Mattie got ready to go inside. Tom’s neighbours were all pronounced ‘life extinct’: there were no signs of life and it was obvious that they had been dead for some hours. The paramedics had looked visibly shaken and he couldn’t say he blamed them because he was plain traumatised.

Lucy waited with Mattie for them to come out. The sombre looks on the paramedics’ faces told her everything she needed to know. This scene was going to give her bad dreams for the rest of her life. Had the father lost it and killed his family, then himself? Lucy nodded at Tom, who had followed the paramedics out, his face drained of colour. Then she stepped through the doorway with Mattie behind her.

Her first thought was what a beautiful home this was and how nice it must be to live in a house this spacious. She passed the lounge, glancing through the open doorway to see a large circle of toy cars carefully positioned on the carpet. She felt her heart ache. They would never be played with again.

Who would want to shoot an entire family? Tom said he hadn’t seen a gun on his first look around, though she doubted that he’d been able to process what he was seeing with the shock of it all. She couldn’t imagine anything worse than being the person to find loved ones or friends murdered like this, in cold blood. Horrific images from another flat with another dead family inside flashed before her eyes. That case had been the one to penetrate her defence system and it had sent her into a complete meltdown. Poor Tom was about to find out how it felt and she wouldn’t wish it on anyone.

Downstairs, it looked as if nothing had happened; in the kitchen there was a wire cooling rack with eleven fairy cakes sitting on it. They had distinctive black-and-white pirate paper cases. Lucy wondered who had eaten the twelfth – had it been Michelle or her son Arran? Had the killer helped himself to one after he’d slaughtered them all? She would get Amanda to check the bins for the wrapper, just to make sure there was no DNA evidence on it. They searched the rest of the ground floor but nothing seemed to be out of place; there were no broken windows or damaged doors.

‘Surely she didn’t go to bed and leave the front door unlocked?’

Mattie shrugged. ‘How else did the killer get inside? Tom said the door was open when he arrived.’

‘Yes, but how irresponsible to go to bed and leave the house unsecured. Unless she didn’t and we discover that the husband killed them, then shot himself. It wouldn’t be the first time, would it?’

‘There’s only one way to find out.’

He pointed to the stairs and let her lead the way. Lucy started to climb them, staying close to the wall in case the killer had used the banister going up and down. It was unlikely, but you could never discount any surfaces from which you might get a half-decent fingerprint. She could smell the metallic tang of blood, even through her mask. She steeled herself for what she was about to see.

When she reached the master bedroom she surveyed the scene quickly. She couldn’t spot a gun; Tom was right. She supposed it was possible that it had fallen from the killer’s hands and under the bed. It took a few more moments for her to let the reality of what had happened here sink in, as she stared at the bodies. It was a scene from her worst nightmares. She realised that the man had been shot in the head from behind, at close range, and she gasped. Why would anyone do this? It was brutal. The horror of being murdered in your own home, unable to protect your family, was incomprehensible.

She stepped aside to let Mattie take a look as she turned away and forced herself to walk on towards the open doorway of the boy’s bedroom. The brightly painted blue walls were covered in spaceship stickers and posters. There was a near complete version of the Milky Way stuck onto the ceiling; hundreds of glow-in-the-dark stars and planets covered it. Someone had taken a lot of time to put these up. This just wasn’t right. She looked all over the room, studying every inch of it except the bed. But when there was nowhere else left to fix her gaze, she made herself focus on it. She felt her heart tear in two. She was never very good with murdered children; thankfully it didn’t happen often.

The small body of the boy lay there, his astronaut duvet tucked around him and a teddy bear close to his head. He was forever frozen in time and space; he would never age another minute. Lucy stepped closer; an urge to shake the kid overwhelmed her. She wanted to shout at him to wake up and tell him the game was over; he’d got her good and proper. Reaching out a gloved hand, she gently touched his arm and recoiled at how stiff it was. There was no waking him up and the bullet hole in his forehead was only confirmation of what she already knew.

‘Come on. We can let CSI get cracking, Lucy.’

She nodded, unable to answer Mattie because she didn’t know whether she could speak without her voice breaking. She followed him to the door and let him go first. Then she turned back and whispered, ‘You’re safe now. My name is Lucy and I promise I will find whoever did this to you and make them pay.’

Then she followed Mattie downstairs, out into the cool night air. Lifting her right arm, she used the sleeve to wipe away the solitary tear that had escaped and was rolling down her cheek.

They walked over to the CSI van, where Tom was standing and Amanda was securing the straps around her boot covers.

‘Bad?’

‘Yes, very. It’s all yours.’

‘Thanks, boss.’ She walked away and Lucy turned to face Tom.

‘I’m so sorry, I don’t know what to say.’

‘It’s just the shock of it all. You don’t expect that to happen to anyone you know. Let alone next door to you. I keep thinking, what if it had been my house? It could be me and my family lying there. What made whoever killed them choose them and not us?’

Desperately wanting to ease the hurt and protect the man standing in front of her, she shook her head.

‘We haven’t ruled out a murder-suicide yet. Catherine will be able to tell us more when she takes a look.’

‘No, I suppose not. But he was a good guy. Why would he want to kill his family? I mean, I know Arran was difficult – he was on the autistic spectrum – but they seemed to have it all under control.’

There was a pause.

‘We’re going to need your clothes, sir,’ Lucy said apologetically. ‘You were the first one on the scene; you know how it is. Just in case? Why don’t you go inside your house and get changed, pop them into a bag and have a stiff drink?’

Tom nodded; he knew the score. They’d probably also want to swab his hands, just to make sure that he hadn’t fired a gun and that there was no gunshot residue underneath his fingernails.

‘It’s okay, Lucy. I’ll get Browning to take me back to the station – he can get my clothes from me, then phone the new boy to come and swab my hands.’

‘I’m so sorry, Tom.’

‘You don’t have to be – I wouldn’t expect anything less of you, Lucy. Your attention to detail is the reason I phoned you in the first place. I want the bastard who has done this caught and I know you’ll catch them.’