We had arrived at my uncle’s workshop, and Spike grasped the handle and gently pushed the door open. If we were hoping to find Mycroft standing there in all his spectral glory, we were disappointed. The room was empty.

“He was just over there.”

Spike closed his eyes, sniffed the air and touched the workbench. “Yeah,” he said, “I can feel him.”

“Can you?”

“No, not really. Where was he again?”

“At the worktop. Spike, what exactly is a ghost?”

“A phantom,” said my uncle Mycroft, who had just materialized, “is essentially a heteromorphic wave pattern that gains solidity when the apparition converts thermal energy from the surroundings to visible light. It’s a fascinating process, and I’m amazed no one has thought of harnessing it—a holographic TV that could operate from the heat given off by an average-size guinea pig.”

I shivered. Mycroft was right—the temperature had dropped—and there he was, but a lot less solid than the previous time. I could easily see the other side of the workshop through him.

“Hello again, Thursday,” he said. “Good afternoon, Mr. Stoker.”

“Good afternoon, sir,” replied Spike. “Word in the Realm of the Dead says you’ve got something to tell us.”

“I have?” asked Mycroft, looking at me.

“Yes, Uncle,” I told him, “You’re a Nonrecurring…um—”

“Nonrecurring Informative Phantasm,” put in Spike helpfully. “An NIP, or what we call in the trade Speak Up and Shut Down.”

“It means, Uncle,” I said, “that you’ve got something really important to tell us.”

Mycroft looked thoughtful for so long that I almost nudged him before I realized it would be useless.

“Like what?” he said at last.

“I don’t know. Perhaps a…philosophy of life or something?”

Mycroft looked at me doubtfully and raised an eyebrow. “The only thing that springs to mind is, ‘You can never have too many chairs.’”

“That’s it? You returned from the dead to give me advice on furniture distribution?”

“I know it’s not much of a philosophy,” said Mycroft with a shrug, “but it can pay dividends if someone unexpectedly pops around for dinner.”

“Uncle, please try to remember what it is you have to tell us!”

“Was I murdered or anything?” he asked in a dreamy fashion. “Ghosts often come back if they’ve been killed or something—at least, Patrick Swayze did.”

“You definitely weren’t murdered,” I told him. “It was a long illness.”

“Then this is something of a puzzle,” murmured Mycroft, “but I suppose I’ve got the greater part of eternity to figure it out.”

That’s what I liked about my uncle—always optimistic. But that was it. In another moment he had gone.