I shrugged. "Run them over with a truck. Chop them to bits with an ax. Burn them to ashes. A gun or a baseball bat won't do it."

"This may come as a shock to you, Harry, but I don't have an ax with me. Is there something else? Maybe something that isn't so Bunyan-esque?"

"Plenty," I said. "If you can cut off the flow of energy into them, they'll drop."

"How do you do that?"

"You'd have to ground them out. Running water is the best way, but there needs to be a lot of it. A small stream, at least. I could also probably trap one in a magic circle and cut off any energy from getting to it. Either way, they'd just fall over, plop."

"Magic circles," Butters shook his head. "And nothing else?"

"Keep in mind that they aren't intelligent," I said. "Zombies follow orders, but they don't have much more intellect than your average animal. You have to outthink them—or the necromancer who is giving them orders. You could also cut off the necromancer's control of them."

"How?"

"Kill their drum."

"Uh, what?"

I shook my head. "Sorry. A zombie… well, it isn't really a person with thoughts and feelings and such, but the corpse is used to being a person. To eating, breathing—and to a beating heart. That's how the necromancer controls them. He plays a beat or some kind of rhythmic music, and uses magic to substitute his beat for the zombie's heartbeat. He links himself to the beat, the beat to the zombie's heart, and when the necromancer gives a command, as far as the zombie is concerned it's coming from inside him and he wants to do it. That's how they can control them so completely."

"That book," Butters said. "Grevane kept drumming it against his leg. And then outside, that huge bass woofer in that Cadillac."

"Exactly. Make the beat stop or get the zombies out of earshot, and he loses control of them. But that's really dicey."

"Why?"

"Because it won't destroy the zombie. It just frees it from the necromancer's control. Anything could happen. It could just shut down, or it could start killing everyone it sees. Totally unpredictable. If I'd stopped him from drumming in the exam room, they might have killed us all. Or run off in different directions to hurt other people. We couldn't afford to take the chance."

Butters nodded, absorbing this for a minute. Then he piped up with, "Grevane said you weren't a Warden. What is a Warden?"

"Wardens are the White Council's version of cops," I said. "They enforce the Laws of Magic, bring criminals in for a trial, and then they chop off their heads. Sometimes they get enthusiastic and just skip to the chopping."

"Well. That doesn't sound so bad."