“Jacob and I have been studying in the old library,” said the Armourer. “When I can tear him away from his . . . other pursuits. And we’ve turned up some quite remarkable items. A number of books thought to be long lost, or destroyed, a number of ancient maps of dubious provenance but exciting possibilities . . . and a handful of lost and quite legendary treasures. That . . . is Merlin’s Glass. It disappeared from the Armageddon Codex in the late eighteenth century, under somewhat murky circumstances. Jacob discovered it inside a hollowed-out book about voles.”

“Don’t even know what made me look there,” Jacob said cheerfully. “I was just looking for something with dirty pictures.”

“Hold everything,” said Molly. “Though not literally in your case, Jacob. Merlin’s Glass. Are we talking about the Merlin?”

“Oh yes,” said Jacob.

“He was a Drood?” said Molly.

“Hardly,” said the Armourer. “We do have our standards. No, he was Merlin Satanspawn, the Devil’s only begotten son. Born to be the Antichrist, but he refused the honour. He always had to go his own way . . . But according to some quite fascinating records in the old library, he did work with the family, on occasion. When it suited him. And apparently he owed us a favour, and repaid it by gifting us that mirror.”

Molly reached out for it, and I handed it over. She muttered some Words over the mirror, made a few quick gestures, and even held it upside down and shook it in the hope something might fall out, but nothing happened. Molly sniffed and handed the mirror back to me.

“All right,” she said. “I’ll bite. What’s it supposed to do?”

“It can be used to make contact with other members of the Drood family, in the past or the future, to ask them for advice or information.”

There was a pause, and then Molly said, “No offence guys, but I think you got stiffed on the deal. I mean, it’s not the most useless magic object I’ve ever seen . . . but it comes pretty damned close.”

“You’re a witch,” the Armourer said kindly, “and therefore used to thinking mainly in terms of the here and now. The Glass has many uses. Vital information lost in this time can be found in the past, before it was lost. Or in the future, after it has been rediscovered. The greatest family tacticians, of the past or the future, are now ours to consult. We can even take specific advice from the future, on which matters to pursue and which are best left strictly alone . . .”

“If this Glass is so useful,” I said, “how did it happen to go missing for so long?”