‘Something you must have noticed in the chapel: two elaborate pillars. One is called the Mason’s Pillar, the other the Apprentice Pillar. The story goes, the Master Mason decided to go abroad to study the design for the pillar he was to construct. But while he was away, one of his apprentices had a dream about the way the finished pillar should look. He got to work and created the Apprentice Pillar. When the Master Mason returned, he was so jealous he went after the apprentice and bludgeoned him to death with a mallet.’

‘So the mason’s dream ended with the pillar?’

‘That’s right.’

Siobhan went through the story in her head. ‘It all fits,’ she said at last. ‘Thanks so much, sir.’

‘Mission accomplished?’

‘Well, not quite. I’ve got to go.’

‘Call me some other time, Siobhan. I want to hear how it ends.’

‘I will. Thanks again.’

She ran both hands through her hair. A corny beginning where the mason’s dream ended. Rosslyn Chapel. It was in the village of Roslin, about six miles south of the city. Siobhan picked up her phone again, ready to call Grant … But then she put it down. Over at the laptop, she sent an e-mail to Quizmaster:

The Apprentice Pillar, Rosslyn Chapel.

Then she waited. She drank a cup of weak coffee, using it to wash down two paracetamol. She went into the bathroom and had a shower. She was rubbing her hair dry with a towel when she walked back into the living room. There was still no message from Quizmaster. She sat down again, chewed her bottom lip. They hadn’t needed to go to Hart Fell: the name had been enough. In less than three hours, time would be up. Did Quizmaster want her to go to Roslin? She sent another e-mail:

Do I stay or do I go?

Again she waited. The second cup of coffee was weaker than the first. The jar was empty now. If she wanted anything else to drink, it would have to be camomile tea. She wondered if Quizmaster could have gone somewhere. She got the feeling he would take a laptop and mobile with him wherever he went. Maybe he’d even run it twenty-four/ seven, just like she’d been doing. He’d want to know when messages came through.

So what was he playing at?

‘Can’t risk it,’ she said out loud. One final message: I’m going to the chapel. Then she went to get dressed.

She got into her car, placed the laptop on the passenger seat. She thought again about calling Grant, but decided against it. She’d be all right; she could take any flak he threw at her …

… you don’t want to share. And if that doesn’t sound like Rebus, I don’t know what does.