Hanson expected Step to become frustrated, but he gave a slightly weary smile. ‘Issa thinks I encouraged him the last time round, or maybe even matchmade him, because I was the one who put them in touch. Alex and Sarah. I had zero idea anything would happen. I’d just met her at work, and she’d told me she was unhappy with her weight and fitness.’ He shifted very slightly again, leaning forwards and resting an arm on each knee. ‘If Issa wants to believe that Alex’s straying only happened because of me, then in some ways I’m happy for him to think so. Alex just had fleeting moments when he wished he’d fallen in love with a woman instead. Deep down he knows – he knew – that any acceptance from his family would be hollow, and he wanted to make a life with Issa.’

‘So you didn’t feel jealous when he hooked up with someone?’ Hanson asked.

‘No,’ Step said, back in control now. ‘Alex was a really wonderful friend, and I miss him like crazy. But I never in a million years thought of him as anything else.’

Step asked if they’d checked the time of his return on Friday evening with his wife, which Lightman had done previously. But the chief asked Hanson to put the question to his wife again, so she left them in the sitting room while she went to find her.

Karen Conti was trying to bake cookies with two kids who seemed more interested in eating smarties out of the packet. She answered over her shoulder, looking worried by the question. But she seemed quite definite that Step had been home by twelve thirty.

This all meant there was no justification for bringing Step into the station. Given that his own knife was sitting there, unused, and that they had little more to point at him than an observation from April Dumont, they had to leave it.

The other members of Step and Alex’s group knew about that weapon, too, Hanson thought. That was where they needed to look.

As soon as they were back at the station, Hanson opened up the data file from Alex’s phone. By Step’s account, the knife had been given to him on the nineteenth, so she set her date range from January the tenth to the nineteenth.

She vaguely heard Lightman tell the DCI, ‘Issa Benhawy was in Blue Underground on Friday, looking for Alex. One of the bar staff spoke to me.’

Hanson’s head snapped up. She hadn’t thought about Alex’s husband in some while. He seemed such an unlikely violent killer: a pacifist who hated any kind of aggression. So much so that his husband had hidden that he was buying a knife for Step.