If someone was really studying the craft then they’d need Cuthbertson’s A Modern Commentary on the Great Work. Written in 1897 in English, thank God, and no doubt welcomed with open arms by every frustrated student who’d ever tried to light his room with a werelight. I looked in the box and found a copy of Cuthbertson right under a huge modern desktop Latin dictionary and grammar—it was nice to know I wasn’t the only one who needed help. The Modern Commentary was, like the Principia, old and well used. I flicked through its pages and came across a faded stamp thirty pages in—an open book surrounded by three crowns and encircled by the words BIBLIOTHECA BODLEIANA. I checked the Principia and found a different stamp, an old-fashioned drawing compass surrounded by the words SCIENTIA POTESTAS EST QMS. I turned to the frontispiece and found a faint rectangular discoloration. My dad had books with that same pattern, ones that he’d jacked from his school library when he was young. The mark was from the glue that once held a folder into which a library card would have fit back in the day when dinosaurs roamed the earth and computers were the size of washing machines.

I carefully emptied the packing case. There were six more books that I recognized as being authentically related to magic, all of them with the BIBLIOTHECA BODLEIANA library stamp.

I assumed that stamp referred to the Bodleian Library, which I vaguely remembered was in Oxford, but while I didn’t recognize the second stamp I did recognize the motto. I dialed the Folly. The phone rang several times before being picked up. “It’s Peter,” I said. There was silence at the other end. “I need to speak to him right away.” I heard a clunk as the receiver was put down by the phone. As I waited I thought it was about time that I bought Nightingale a proper phone.

When Nightingale picked up I explained about the books. He made me list the titles and describe the stamps. Then he asked if Stephanopoulis was available.

I called her and offered her the phone. “My governor wants a word,” I said.

While they talked I started bagging the books and filling out the evidence tags.

“And you think this makes it more likely?” she asked. “Fair enough. I’ll send the boy over with the books. I expect you to maintain chain of custody.” Nightingale must have assured her that we would be as scrupulous as any Home Office lab because she nodded and handed the phone back to me.

“I think,” said Nightingale, “that we may be dealing with a black magician here.”

Chapter 5 - The Night Gate