Ava knocked on the door. No answer. She knocked harder then gave his mobile a call. When that, too, received no response, she tried his landline. That was engaged, which was strange in the small hours, given that she couldn’t hear his voice inside. It was possible that someone from MIT was calling to update him, but then surely he’d have come to the door. She hadn’t wanted to use her key on his flat door. It was one thing letting herself into the stairwell to the apartments, but going further was an invasion of his privacy. More than that, it assumed a connection between the two of them that was no longer active, if indeed it had even been real.

She caught movement from behind the door’s eyehole. No more than the briefest darkening of the dim light beyond, a flicker, but the flat was definitely occupied.

‘Luc,’ she called quietly. ‘It’s me. I should have come before now, I realise that, but something’s happened. Please, open the door.’

Waiting proved futile. Her watch showed she’d already wasted half the time she’d allocated. In five minutes, another police car would arrive to get her to the station. Perhaps Callanach was being stubborn, only that wasn’t like him. What concerned her more was the prospect that his current suspensions – in all but name – had sent him into the same spiral of depression that had disabled him so badly at the end of his time at Interpol. If that were the case, there was only one thing to do.

‘I’m coming in,’ she said as she slipped her key into the lock and walked into the dark living room, clicking the door shut behind her.

There was a light on in the bedroom.

‘Luc,’ she called. ‘It’s just me. I apologise for letting myself in, but it’s important. I hope you don’t …’

Callanach was on the bed, bare-chested but wearing jeans, sitting with his legs stretched out but his arms folded. Perched on the window seat, one hand wrapped around something Ava couldn’t quite see, was Astrid Borde.

‘Hello,’ Astrid said brightly. ‘Luc was hoping you’d just go away, but I’m glad you’ve come in. Things were getting rather dull. You don’t seem surprised to see me here.’

‘I’m not,’ Ava smiled. ‘You appeared in some footage I was watching earlier today. You have quite an unmistakeable figure.’

‘And you have a key to Luc’s flat. Why is that?’

She addressed the question to Callanach, who simply shrugged.

‘What, no attempt at excuses? No elaborate tales of working late together? Luc, are you not going to defend DCI Turner’s honour?’

‘DCI Turner can defend herself,’ Callanach said. ‘She has a key because we’re friends. If you’re looking for anything more than that, I’m going to have to leave it to your imagination.’