‘The likelihood is it will be the former, but we have to rule out the latter,’ he advised. ‘The information was specific to the left-luggage facility, so we’ll start there, but if we come up blank, we’d better widen the search.’

The two handlers fitted their animals with the bright blue harnesses that communicated to the dogs that it was time to go to work. They proceeded inside through the main archway, Cairns setting off a few moments behind them.

After a couple of paces he stopped and turned to Catherine.

‘You coming?’ he asked.

‘Sure,’ she replied, though she felt a little apprehensive.

She wondered about this instinctive reluctance. Was she concerned that he was inviting her to ride shotgun so that she would find herself sharing the blame if it turned out to be a false alarm? Then she passed the hollowed-out World War II bomb that stood just inside the main entrance and remembered a more prosaic reason for why she might not fancy a trip to left-luggage.

Trying to stay calm and professional, her mind sought out a distracting thought, then promptly wished it hadn’t found one.

She and Drew used to meet at the bomb when they were first going out together, coming off of different trains. She could still remember how it felt to watch the crowd and suddenly see him appear, walking towards her. The age difference seemed smaller as they got older, but he really did seem like her toy boy back then: Drew twenty-two and she thirty-one. They both thought their relationship was frivolous and uncomplicated, neither sizing the other up with a view to long-term suitability: in her case because he was just meant to be a bit of diversion, a rebound fling; and in his because, well, he was twenty-two. That was what took the pressure off and let her just enjoy being with him. It was fun. She was fun.

Then.

He hadn’t come home last night. He called around seven to say that some of the London office were booked into the Mal in Leith, and he was going to do likewise so that they could all have a late one. She had told him sure, enjoy yourself, make the most of it. The irrational side had receded; she wasn’t scared of him getting tipsy and lunging for someone else – or not as scared. But she felt the news that he wasn’t coming home as a blow. He wasn’t doing it to get at her, but her guilty conscience couldn’t help but interpret it as a deserved punishment, thinking that if she had been a little nicer to him of late, he’d have taken that last train.