Vestigium is the imprint magic leaves on physical objects. It’s a lot like a sense impression, like the memory of a smell or sound you once heard. You’ve probably felt it a hundred times a day but it gets mixed up with memories, daydreams, and even smells you’re smelling and sounds you’re hearing. Some things, stones for example, sop up everything that happens around them even when it’s barely magical at all—that’s what gives an old house its character. Other things, like the human body, are terrible at retaining vestigia—it takes the magical equivalent of a grenade going off to imprint anything on a corpse.

Which was why I was a little bit surprised to hear the body of Cyrus Wilkinson playing a saxophone solo. The melody floated in from a time when all the radios were made out of Bakelite and blown glass and with it came a builder’s-yard smell of cut wood and cement dust. I stayed there long enough to be sure I could identify the tune and then I stepped away.

“How did you spot this?” I asked.

“I check all the sudden deaths,” said Dr. Walid. “Just on the off chance. I thought it sounded like jazz.”

“Did you recognize the tune?”

“Not me. I’m strictly prog rock and the nineteenth-century romantics,” said Dr. Walid. “Did you?”

“It’s ‘Body and Soul,’ ” I said. “It’s from the 1930s.”

“Who played it?”

“Just about everybody,” I said. “It’s one of the great jazz classics.”

“You can’t die of jazz,” said Dr. Walid. “Can you?”

I thought of Fats Navarro, Billie Holiday, and Charlie Parker who, when he died, was mistaken by a coroner for a man twice his real age.

“You know,” I said, “I think you’ll find you can.”

Jazz had certainly done its best for my father.

YOU DON’T get vestigia on a body like that without some serious magic, which meant either somebody did something magical to Cyrus Wilkinson or he was a user himself. Nightingale called civilians who used magic practitioners; according to him practitioners, even amateurs, frequently leave evidence of their “practice” at their homes, so I headed over the river to the address listed on Mr. Wilkinson’s driver’s license to see whether there was anyone who loved him enough to kill him.