Anger flashed through me. "I'm tempted to let you come, just for that. But you don't grasp the danger. You could die. Tonight."

"I don't think so."

I picked up the Ziploc bag containing the white powder and the FedEx envelope and held it out to her. "A few minutes ago I received a letter from Fielding. This powder was in the envelope."

She shrugged. "It looks like sand. What is it?"

"I have no idea. But I'm afraid it might be anthrax. Or whatever killed Fielding."

She took the package from me. I thought at first she was examining the powder, but she was reading the label on the FedEx envelope.

"This says the sender is Lewis Carroll."

"That's code. Fielding couldn't risk putting his name into the FedEx computer system. The NSA would pick that up immediately. He used 'Lewis Carroll' because his nickname was the White Rabbit. You've heard that, right?"

Rachel looked as if she were really thinking about it. "I can't say that I have. Where's this letter?"

I motioned toward the front room. "In a plastic bag on the couch. Don't open it."

She bent over the note and quickly read it. "It's not signed."

"Of course not. Fielding didn't know who might see it. That rabbit symbol is his signature."

She looked at me with disbelief. "Just take me along, David. If what I see supports what you've told me, I'll take all your warnings seriously from this point forward. No more doubts."

"That's like throwing you into the water to prove there are sharks in it. By the time you see them, it's too late."

"That's always how it is with these kinds of fantasies."

I went and got my keys off the kitchen counter. Rachel followed at my heels. "All right, you want to come? Follow me in your car."

She shook her head. "Not a chance. You'd lose me at the first red light."

"Your colleagues would tell you it's dangerous to accompany a patient while he chases a paranoid fantasy. Especially a narcoleptic patient."