"Not a feud," Bob says. "In a feud, both sides fight. This is more like me screaming and running away before she rips me apart."

I shook my head. "Man, Bob. I know you can be an annoying git when you want to be one-but what did you do to make Mab mad at you?"

"It isn't what I do, Harry," Bob said in a very small voice. "It's what I know."

I lifted an eyebrow. It took a lot to make the skull flinch. "And what is that, exactly?"

The lights in the eye sockets dwindled to tiny pinpoints, and his voice came out in a whisper. "I know how to kill an immortal."

"Like Maeve?" I asked him.

"Maeve," Bob said. "Mab. Mother Winter. Any of them."

Holy crap.

Now, that was a piece of information worth killing for.

If the skull knew how to subtract the im from immortal, then he could be a source of danger to beings of power throughout the universe. Hell, he was lucky that gods and demons and supernatural powers everywhere hadn't formed up in a safari and come gunning for him. And it meant that maybe I wasn't looking at an impossible mission after all.

"I'd like you to tell me," I said.

"No way," Bob said. "No way. The only reason I've been around this long is that I've kept my mouth shut. If I start shooting it off now, Mab and every other immortal with an interest in this stupid planet are going to smash my skull to powder and leave me out to fry in the sun." The eyelights bobbed toward the rear compartment. "And there are too many ears around here."

"Toot," I said, "get everybody out of the car. I need privacy. Make sure no one gets close enough to eavesdrop."

"Aw," Toot complained from the rear compartment. "Not even me?"

"You're the only one I can trust to keep those other mugs from doing it, Major General. No one overhears. Got it?"

I could practically hear the pride bursting out of his voice: "Got it!" he piped. "Will do, my lord!"

He rolled down a window and buzzed out. I rolled it back up and took a look around the hearse with both normal and supernatural senses, to be sure we were alone. Then I turned back to the skull.

"Bob, it's just you and me talking here. Think about this. Mab sends me off to kill Maeve, something that would be impossible for me to do on my own-and she knew that you know how to do it. She knew the first thing I would do is come back here as the first step in the job. I think she meant for me to come to you. I think she meant for you to tell me."

The skull considered that for a moment. "It's indirect and manipulative, so you're probably onto something. Let me think." A long minute went by. Then he spoke very quietly. "If I tell you," he said, "you've got to dosomething for me."

"Like what?"

"A new vessel," he said. "You've got to make me a new house. Somewhere I can get to it. Then if they come after this one, I've got somewhere else to go."

"Tall order for me," I said soberly. "You've basically got your own little pocket dimension in there. I've never tried anything that complicated before. Not even Little Chicago."

"Promise me," Bob said. "Promise me on your power."

Swearing by one's power is how a wizard makes a verbal contract. If you break your word, your ability with magic starts to fray, and if you keep doing it, sooner or later it'll just wither up and die. A broken promise, sworn by my power, could set me back years and years in terms of my ability to use magic. I held up my hand. "I swear, on my power, to construct a new vessel for you if you tell me, Bob, assuming I survive the next few days. Just . . . don't expect a deluxe place like you have now."

The flickering eyelights flared up to their normal size again. "Don't worry, boss," Bob said with compassion. "I won't."

"Wiseass."

"Right, then!" Bob said. "The only way to kill an immortal is at certain specific places."

"And you know one? Where?"

"Hah, already you're making a human assumption. There are more than three dimensions, Harry. Not all places are in space. Some of them are places in time. They're called conjunctions."

"I know about conjunctions, Bob," I said, annoyed. "When the stars and planets align. You can use them to support heavy-duty magic sometimes."

"That's one way to measure a conjunction," said the skull. "But stars and planets are ultimately just measuring stakes used to describe a position in time. And that's one way to use a conjunction, but they do other things, too."

I nodded thoughtfully. "And there's a conjunction when immortals are vulnerable?"

"Give the man a cookie; he's got the idea. Every year."

"When is it?"

"On Halloween night, of course."

I slammed on the brakes and pulled the car to the side of the road. "Say that again?"

"Halloween," Bob said, his voice turning sober. "It's when the world of the dead is closest to the mortal world. Everyone-everything-standing in this world is mortal on Halloween."

I let out a low, slow whistle.

"I doubt there are more than a couple of people alive who know that, Harry," Bob said. "And the immortals will keep it that way."

"Why are they so worried?" I asked. "I mean, why not just not show up on Halloween night?"