‘You might imagine that we panicked, but we didn’t,’ she says, almost proudly. ‘Instead, I went back into the cellar after I heard the shot and we stayed there for about an hour talking through what we should do. The first decision we made was to stick together and the second was to take you with us and make everyone believe that you were Charlotte. Then we decided to leave the bodies there and go. First we made sure not to leave any trace of ourselves behind. We wiped our prints from the hammer and the shotgun and staged it to look like Simon killed Amanda and then himself. Then we took you home, packed up, and went to Sunderland where the police called us a couple of days later to tell us your parents had been killed and you were missing. Your nan was suffering early-stage dementia back then so it was easy to convince her we’d been there longer than we had. So, we didn’t become suspects.’

A deep frown forms on Charlotte’s face and tears glisten on her cheeks.

‘I don’t understand,’ she says. ‘If this all happened in the cellar why did you want to move here?’

‘I didn’t want to,’ Mary replies, flicking her head towards Robert. ‘He persuaded me to after your nan died and we came into some money. It was cheap and he liked the idea of being his own boss. But as you know, I’ve never liked living here. It creeps me out. That’s why we eventually got the cellar door replaced with a wall. Plus, we couldn’t risk you finding our real daughter.’

Charlotte’s eyes widen with alarm. ‘What do you mean?’

‘We brought her here with us and buried her body beneath the floorboards,’ Mary says. ‘We wanted her close to us. The memorial stone down there is for her and not for your real parents. Nobody but us knows she’s there.’

Mary falls silent again and she and Charlotte stare at each other. Charlotte is clearly devastated whereas Mary looks almost pleased with herself.

Robert switches his gaze between the two of them and it feels like his heart is being squeezed by an iron fist.

He knows there’s no way back from this. Mary has seen to that. Her fragile state of mind, combined with her anger over Charlotte ruining Christmas, has pushed her over the edge and released a mass of inner demons. She probably feels that Charlotte has finally got what was coming to her. Payback for years of Mary having to tolerate her bad behaviour.

Suddenly Charlotte finds her voice. ‘I hate you both so much. I’ve always suspected that I wasn’t wanted and that you didn’t love me. And now I know why.’