The Stepson: A psychological thriller with a twist you won't see coming

He let go her hand and stood, and walked to the TV that was set into the wall, and turned to face her, as if standing on a stage giving a lecture. She often found that her clients physically moved away from her when they first started to open up. It was as if they needed space around them to feel safe.

‘They had gone,’ he said, staring at her. ‘They’d just disappeared, all three of them, into thin air. When I got back home that day . . . I’d been in Edinburgh doing museums and galleries and stuff with my friend Andy and his mum. I was looking forward to telling Dad all about it. Then the house . . . the house was in darkness, and they’d gone. The police decided there were no suspicious circumstances and they’d left of their own accord, and it wasn’t a police matter. I was sixteen and theoretically an adult, so it wasn’t a case of child abandonment. But no way would Dad have done that to me!’

He turned towards the river, then towards the marina, and then he suddenly walked off into the corridor and came back with one of the framed photos, the one of him and his dad with their arms round each other.

‘Look at us!’ He thrust it into her hands. ‘Dad and I – we were really close. I loved him so much, and he loved me. I know he did. He would never, ever have just gone off like that, leaving me all alone. Leaving me not knowing what had happened.’ He choked on a deep breath.

‘You can see how much you love each other,’ Lulu said quietly, touching the glass over the photo with gentle fingertips.

‘It was like the Mary Celeste, Lulu! Nothing was disturbed, which is why the police presumably ruled out violence. But it didn’t add up. They hadn’t taken their passports or withdrawn any money from their bank accounts. I know the breakfast things were cleared up before I left that morning, so why were there three mugs and three bowls and three spoons on the table, when it was just the two of them in the house, apart from Isla? One of the rings on the hob was on. There was a pan of water and oatmeal next to it, as if Dad had been about to make some porridge when . . . whatever happened happened.’

‘You think your stepmother did something to your dad and your sister,’ she prompted.

‘There’s no other explanation that makes sense.’

‘But does that explanation make sense?’ Lulu made her voice gentle. ‘She was a small woman, wasn’t she? Could she really have done it?’

‘She could have had an accomplice – hence the extra mug and bowl and spoon. Or maybe she was trying to set me up for it, make it look like I was there when it happened. She’d been a young offender, for God’s sake – convicted of GBH. She was violent. I was scared of her, this tiny woman . . . When we were alone together, she used to stare at me, like she was . . . I don’t know. Like she wanted me gone. And she did things like trample a set of plastic spoons she had and try to blame me. She used to call me a wee bastard, a wee fucker . . . Okay, I was an annoying brat, and I definitely went out of my way to push her buttons, but I can see now that she really overreacted to that. She was scary, Lulu.’

Oh God. ‘What did your dad make of her behaviour?’

‘Dad was a bit like you.’ A small smile. ‘Always saw the best in people.’

He turned away from her and paced to the glass wall, his back to Lulu. ‘I should have tried harder to make Dad see what she was really like.’

‘But you don’t know that Maggie was responsible. You don’t know what happened to them. Probably you’ll never know – and maybe you’re going to have to accept that.’

‘There was blood.’ Nick turned back to face her. ‘On the drawing room carpet and in the hall. When the police had it tested, they found it had Maggie’s DNA. They concluded it was irrelevant to what had happened, that Maggie maybe cut her finger or something. But I think that must be where . . . where she did whatever she did to Dad. He must have put up some sort of a fight, but – he wouldn’t have wanted to hurt her, you see. Everything in him would have been screaming that he couldn’t hurt a woman.’

There was a long silence. Then Lulu said, ‘It must have been so hard, losing them and then being packed off to boarding school, living amongst strangers . . .’

His face twisted. ‘Dear Auntie Yvonne and Uncle Michael were kind enough to arrange that for me. Yvonne got herself made what they call a judicial factor loco absentis, which let her take control of Dad’s affairs until he was declared officially dead. She organised the letting of the house to give me an income. And they allowed me to stay with them for a week at Christmas and a week in the summer, but not at Easter or half term or any other time. They pretty much washed their hands of me.’

‘Your whole world imploded,’ she summarised, going to him and pulling him into a hug as the tears came, for both of them.

‘I’ve blown it, haven’t I?’ he sobbed. ‘I’ve pushed you away!’

She wasn’t going to lie to him. She took a deep breath. ‘You haven’t blown it, Nick, but I do think the way this relationship is developing is unhealthy. Getting Harry to spy on me . . .’ To soften the impact of her words, she rubbed his back. ‘That crossed a line.’

‘Oh God! Please give me another chance! I’ll never do anything like that again!’

She kept rubbing his back. ‘That’s easy to say. But the first step in making a change is to accept that you have a problem. There’s nothing terrible about having a mental illness.’ She had to tread gently here. ‘It doesn’t mean that you’re like Maggie.’

He made a wordless sound and broke away from her, staring into her eyes as if scared of what he might see there.

‘There’s nothing to be ashamed of in admitting that you need help.’ She took both his hands in hers.

It was strictly against the code of ethics she’d signed up to, to treat a member of one’s own family. She could lose her licence for this. But so what? She wasn’t sure she even wanted to be a therapist any more. And anyway, Nick was more important.

‘I love you, Nick. I’ll always love you. You’re not going to lose my love by letting me help you through this. Quite the opposite. Please, will you let me help you heal?’

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