Katerina Diamond: The Promise: The twisty new thriller from the Sunday Times bestseller, guaranteed to keep you up all night

He managed to clear a fair bit of the muck off the inside of the window. Opening it, he slid his arm through to the outside and wiped that as well. It was smeared and kind of disgusting, but at least now he could see outside. The tree house looked directly into the neighbour’s back garden and onto the rear of their house. Connor smiled as he saw a couple, presumably his new neighbours, kissing against the countertops in the kitchen.

He looked around the tree house and felt a little glimmer of hope. There was no way his father would make it up here – he had a place where he could be by himself, without his father’s watchful eye, without the hand on his shoulder, without feeling like he was to blame for everything that was wrong in the world.

Connor shuffled back against the wall and sat down with his beer in his hand, thinking about the different things he was going to have to get used to here in England. His father had always maintained he would never come back, but when his parents had died and left him the house, it seemed like a logical move after the incident back at home. If Connor was honest, he needed a change too. He couldn’t carry on being the person he was in California; people had started to notice that he wasn’t the same as them, and he couldn’t stand that.

He pulled out the Zippo his father had given him as a gift for his sixteenth birthday and struck the wheel with his thumb, watching the flame flickering in the light breeze that ran through the empty tree house. He pulled out a cigarette and lit it before peering through the window again. The woman next door was up on the countertop now, her legs wrapped around her partner’s waist, his trousers around his ankles. Upstairs, he could see into what looked like a girl’s bedroom; she was sitting at her dressing table, with a lamp on. It was the girl he had seen earlier when they arrived. As Connor watched, she undid the plait in her hair and started to brush it out.

The loud pops of fireworks in the distance unsettled Connor, and he saw the sky to the east flashing pink. People had already started to set them off in the run-up to Bonfire Night. Looking back at the girl, he could see a blank expression on her face which was reflected in her dressing-table mirror. He wondered if she could hear what was happening downstairs, or outside. The girl stood up and walked over to her window, her face changing colour as the fireworks erupted overhead. Connor shrank back, making sure she didn’t know he was in there. For now, he just wanted to watch them – to see what a normal family did. Something he had never known.

The girl had long mousy hair and round glasses, around his age. She stared out of the window into her own garden, which was comprised of a tidy lawn and a decked patio with black plastic furniture and a big orange parasol. Fixating on a point in the distance, she just stared for a while. Her face was empty, not interested, not sad – nothing. After a few seconds, she pulled a book from a shelf in her room and then got into her bed. Connor continued to watch her; she read for less than five minutes and then flipped a switch that turned her reading light into a soft pink glowing orb. It was only then that he realised the dusk had turned to night-time, he had never known it to get this dark so early back home, it was barely six in the evening.

He turned his attention back to the couple downstairs, who were still grabbing and pawing at each other desperately until he slumped against her and she pushed him away. The urgency gone, they redressed and disappeared back into the parts of the house that he couldn’t see. He watched the sky for a while until the popping slowed to a stop and the sky returned to its lifeless dusky black.

Reluctantly, Connor climbed back out of the tree house and down the tree. It was harder than going up, but still it just reassured him that his father would never be able to make the journey with his leg. He walked back through the garden to his father, who was sitting in the almost-darkness, from the looks of it on his fourth beer already. It wasn’t as cold as he expected it to be, from the stories he had heard it did nothing but rain over here. So far his denim jacket had been enough to keep him warm.

‘Anything good up there?’

‘Like what?’

‘Me and your uncle used to read comics and pornos up there, wondered if there was anything still knocking around.’

‘Nope. It’s empty.’

Connor pulled at the back door handle to go inside and check the rest of the house out; he hadn’t even seen his bedroom yet.

‘Listen, Con, this is a chance for both of us to do something right,’ his father said.

Connor froze.

‘I know, Dad.’

‘Try not to fuck things up at school.’

‘I’ll try.’

‘You better try pretty fucking hard; we can’t just move to a new country every time you do.’

‘I will, Dad, I promise.’

‘You’d better get an early night. You need to get proper rest before you start school on Monday.’

Connor took a deep breath. At least here in Exeter he would get to be who he wanted; he would make himself, he would decide what people saw. What they knew and didn’t know. He would make sure no one found out about him.

Adrian was sitting in the interview room opposite Sarah Lawson, Erica’s sister and ICE contact. Imogen walked in and sat down opposite Sarah, who looked like a slightly older version of Erica, although her hair was tidier from the photos they had seen. Adrian noted the puffiness around her eyes; she probably hadn’t slept since her sister had been found – as she had been the one to find her.

Imogen noted the date and time, plus persons present for the recording, and then nodded at Adrian to start.

‘How are you holding up?’ Adrian asked, recognising that look on her face. Grief. Since he had lost someone important, the word bereft had taken on a new meaning. Sarah was obviously bereft, missing something, a touch of confusion mixed with sadness. Like walking into a room and trying to figure out what you went in there for, then realising that you would never find it, because it was gone forever.

‘I … I can’t believe it.’

‘We’re sorry for your loss.’ Adrian said the hollow words. He could feel Imogen’s focus on him as he spoke; he faltered for a moment as Lucy popped into his mind.

‘Your sister appeared to be dressed to go out. Could she have been on a date? Did she mention anything like that?’ Imogen said, stepping in to speak, to give him a moment.

‘No, she didn’t say anything about it.’

‘Were you not close then?’ Adrian said.

‘We were. We were really close. I don’t know why she didn’t tell me.’

‘So, you have no idea who your sister was meeting? She didn’t mention anyone to you?’ Imogen said.

‘I swear I have no idea. If I did I would tell you!’ Sarah’s voice cracked as she spoke. The tears started to gather at the edges of her eyes. She was on the brink of losing it altogether.

‘Is there anyone else she was likely to confide in? Did she have a best friend?’

‘I was her best friend! I don’t know why she didn’t tell me if she was meeting a man,’ Sarah said again.

Adrian sighed. ‘There could be lots of reasons why she wouldn’t tell you, Sarah, maybe she didn’t want you to know because she wasn’t sure it was going to go anywhere. I know this is difficult, but the more you can tell us the better. At this point we are just trying to build a picture of Erica. She’s the victim here and there’s a reason she was targeted. The more we know about her, the more likely it will be that we can find out why that was.’

‘Was she sexually assaulted?’ Sarah said, her body tense, as though she almost didn’t want to know the answer. ‘Did he rape her? I asked but no one would tell me.’