“There is an amulet, on a necklace,” Kirsten began suddenly, and Jesse and I both gave a little start. I turned halfway in my seat, my shoulders against the window so I could look at her. She was tilting her head, frowning to herself. “Wait, let me back up. Rabbi Samuel, the man who was killed last night, was the last protector of the Book of Mirrors. It is now missing.”

“Wait, wait, I know what that is,” I said. “Olivia told me about that. It’s a blank book that works like witches’ scratch paper, right? Don’t all witches have them for notes and stuff?”

“Yes. But this one was special. It belonged to Lilith.”

That meant nothing to me, but Jesse suddenly looked hard into the rearview mirror. He said something in Spanish that sounded a lot like “Save us, God.”

“Who?” I asked, bewildered.

“Lilith. You’ve probably heard the name at some point.”

“Adam’s first wife,” Jesse said grimly. “The succubus.”

I was turned far enough in the seat to see Kirsten roll her eyes, a very un-Kirsten-like thing to do. “Neither of those things are true. However, at various points in history most of the bad things in the world were blamed upon Lilith, so she’s become something of a mythic figure,” she said. “Some people in the Old World even speculated for a while that she was a vampire. Actually, though, Lilith was a witch—possibly the first witch, and almost definitely the most powerful in history.”

Jesse’s shoulders backed down from his ears a little bit. Kirsten opened her enormous purse and pulled out a book with a green cover, some kind of encyclopedia. “I brought this to show you.” She flipped it open, turning pages as she talked. “Lilith was known for her kamias, amulets. They are the magical shortcuts I was talking about. She was very famous for this one: the Transruah.”

She handed the book up to me, and I carefully pulled it through the space between me and Jesse. On the left-hand page I could see the small, penciled illustration: a voluptuous woman in a plain white shift, gazing into the distance. One hand had drifted up to touch her necklace, a simple stone on a leather cord. Jesse glanced down at it too.

“It just looks like a rock,” I said bluntly.

Kirsten frowned at me. “It’s Jerusalem stone. Lilith is part of Jewish history.” She shrugged. “Technically you could infuse any object with magic, but Lilith probably wanted a connection with her heritage.”

“What does it do?” I said. “I’m guessing it doesn’t make perfect bread.”

“No. Transruah literally means ‘spirit transfer.’ Lilith would kill someone with a spell, and that person’s spirit, the essence of their life, would become trapped in the amulet, letting Lilith absorb it. Like”—her hands gestured helplessly in the air for a moment—“like in Ghostbusters, they have that machine to trap and store the ghosts. Only this was the souls of living people, and Lilith was the storage container that held all the spirits.”

Jesse and I exchanged a dumbfounded look. Although her day job was in the entertainment industry, that had to be the first movie reference I’d ever heard from Kirsten, and it happened to be from my favorite movie. This day just kept getting weirder.

“What could she do with them?” I asked. “The spirits?”

“Well, Lilith was able to live for centuries, which is probably where that vampire rumor came from. If her victim was another witch, she could also absorb their strengths for a time.” She shrugged helplessly. “And that’s only what we know about. It’s hard to say which of Lilith’s exploits were because of the Transruah, and which were her own natural power.”

“Where is the thing, the amulet?” Jesse said, quite sensibly.

“In the thirteenth century the Knights Templar finally killed Lilith and destroyed her Book of Shadows, her spellbook. Witches have always believed that they destroyed the Transruah as well.”

“And now you think they didn’t?”

She held up two fingers. “To use the Transruah, you need two things: the amulet itself and the spell to use it. Lilith’s spell. The knights were smart enough to destroy her spellbook, but the spell was also written in the Book of Mirrors. It’s the only complete spell in the book. Witches like me have been protecting the book, moving it around to keep it safe. If someone went to all the trouble to kill Rabbi Samuel and steal the book…”

“Could someone have just made a new amulet?” I said. It didn’t look all that special in the drawing.

“No,” Kirsten said, with sudden vehemence. “I am absolutely certain on this point. Over the centuries, there have been a few attempts, and it’s just not possible. An entire coven of witches as powerful as I am couldn’t have re-created the Transruah. It’s unique.”

“So you think Olivia and her partner got the real amulet somehow, and needed the spell to use it,” Jesse said. He looked thoughtful. “That’s kind of a leap, though, isn’t it? Couldn’t the person who took the Book of Mirrors just be a collector or something?”

“I suppose,” Kirsten conceded. “But without the amulet, it’s just a curiosity, a small piece of history. And more importantly was how Rabbi Samuel died. He was…” She paled considerably, her fingers scrabbling at her neck.

“Drained of blood,” I finished, keeping my voice as gentle as I could.