And I could think of nothing at all to do but eventually close my mouth, scratch my head, and stumble into the house.

There was a soft but very deep and powerful drumbeat, and gladness surged up, born from relief and anticipation of what was to come. And then the horns sounded, and it was very close now, only a matter of moments before it came and then everything would begin and happen again at last, and as the gladness rose into a melody that climbed until it seemed to come from everywhere, I felt my feet taking me to where the voices promised bliss, filling everything with that joy that was on the way, that overwhelming fulfillment that would lift us into ecstasy-

And I woke up with my heart pounding and a sense of relief that was certainly not justified and that I did not understand at all. Because it was not merely the relief of a sip of water when you are thirsty or resting when you are tired, although it was those things, too.

But-far beyond puzzling, deep into disturbing-it was also the relief that comes after one of my playdates with the wicked; the relief that says you have fulfilled the deep longings of your innermost self and now you may relax and be content for a while.

And this could not be. It was impossible for me to feel that most private and personal of feelings while lying in bed asleep.

I looked at the clock beside the bed: five minutes past midnight, not a time for Dexter to be up and about, not on a night when he had planned only to sleep.

On the other side of the bed Rita snored softly, twitching slightly like a dog who dreamed of chasing a rabbit.

And on my side of the bed, one terribly confused Dexter. Something had come into my dreamless night and made waves across the tranquil sea of my soulless sleep. I did not know what that something was, but it had made me very glad for no reason I could name, and I did not like that at all. My moonlight hobby made me glad in my own emotionless way and that was all. Nothing else had ever been allowed into that corner of the dark subbasement of Dexter. That was the way I preferred it to be. I had my own small, well-guarded space inside, marked off and locked down, where I felt my own particular joy-on those nights only and at no other time. Nothing else made sense for me.

So what had invaded, knocked down the door, and flooded the cellar with this uncalled-for and unwanted feeling? What in all the world possibly could climb in with such overwhelming ease?

I lay down, determined to go back to sleep and prove to myself that I was still in charge here, that nothing had happened, and certainly wouldn’t happen again. This was Dexterland, and I was king. Nothing else was permitted inside. And I closed my eyes and turned for confirmation to the voice of authority on the inside, the inarguable master of the shadowy corners of all that is me, the Dark Passenger, and I waited for it to agree, to hiss a soothing phrase to put the jangling music and its geyser of feeling into its place, out of the dark and into the outside. And I waited for it to say something, anything, and it did not.

And I poked at it with a very hard and irritated thought, thinking, Wake up! Show some teeth in there!

And it said nothing.

I hurried myself into all the corners of me, hollering with increasing concern, calling for the Passenger, but the place it had been was empty, swept clean, room to rent. It was gone as if it had never been there at all.

In the place where it used to be I could still hear an echo of the music, bouncing off the hard walls of an unfurnished apartment and rolling through a sudden, very painful emptiness.

The Dark Passenger was gone.

I SPENT THE NEXT DAY IN A LATHER OF UNCERTAINTY, HOPING that the Passenger would return and somehow sure it would not. And as the day wore on, this dreary certainty got bigger and bleaker.

There was a large, brittle empty spot inside me and I had no real way to think about it or cope with the gaping hollowness that I had never felt before. I would certainly not claim to feel anguish, which has always struck me as a very self-indulgent thing to experience, but I was acutely uneasy and I lived the whole day in a thick syrup of anxious dread.

Where had my Passenger gone, and why? Would it come back? And these questions pulled me inevitably down into even more alarming speculation: What was the Passenger and why had it come to me in the first place?

It was somewhat sobering to realize just how deeply I had defined myself by something that was not actually me-or was it? Perhaps the entire persona of the Dark Passenger was no more than the sick construct of a damaged mind, a web spun to catch tiny glimmers of filtered reality and protect me from the awful truth of what I really am. It was possible. I am well aware of basic psychology, and I have assumed for quite some time that I am somewhere off the charts. That’s fine with me; I get along very well without any shred of normal humanity to my name.

Or I had until now. But suddenly I was all alone in there, and things did not seem quite so hard-edged and certain. And for the first time, I truly needed to know.

Of course, few jobs provide paid time off for introspection, even on a topic as important as missing Dark Passengers. No, Dexter must still lift that bale. Especially with Deborah cracking the whip.

Happily, it was mostly routine. I spent the morning with my fellow geeks combing through Halpern’s apartment for some concrete residue of his guilt. Even more happily, the evidence was so abundant that very little real work was necessary.

In the back of his closet we found a sock with several drops of blood on it. Under the couch was a white canvas shoe with a matching blotch on top. In a plastic bag in the bathroom was a pair of pants with a singed cuff and even more blood, small dots of spray that had been heat-hardened.

It was probably a good thing that there was so much of it out in the open, because Dexter was truly not his usual bright and eager self today. I found myself drifting in an anxious gray mist and wondering if the Passenger was coming home, only to jerk back to the present, standing there in the closet holding a dirty, blood-spattered sock. If any real investigation had been necessary, I am not sure I could have performed up to my own very high standards.

Luckily, it wasn’t needed. I had never before seen such an outpouring of clear and obvious evidence from somebody who had, after all, had several days to clean up. When I indulge in my own little hobby I am neat and tidy and forensically innocent within minutes; Halpern had let several days go by without taking even the most elementary precautions. It was almost too easy, and when we checked his car I dropped the “almost.” Clearly displayed on the central armrest of the front seat was a thumbprint of dried blood.

Of course, it was still possible that our lab work would show that it was chicken blood, and Halpern had simply been indulging in an innocent pastime, perhaps as an amateur poultry butcher. Somehow, I doubted it. It seemed overwhelmingly clear that Halpern had done something truly unkind to someone.

And yet, the small nagging thought tugged at me that it was, just as overwhelmingly so, too easy. Something was not quite right here. But since I had no Passenger to point me in the right direction, I kept it to myself. It would have been cruel, in any case, to burst Deborah’s happy balloon. She was very nearly glowing with satisfaction as the results came in and Halpern looked more and more like our demented catch of the day.

Deborah was actually humming when she dragged me along to interview Halpern, which took my unease to a new level. I watched her as we went into the room where Halpern was waiting. I could not remember the last time she had seemed so happy. She even forgot to wear her expression of perpetual disapproval. It was very unsettling, a complete violation of natural law, as if everyone on I-95 suddenly decided to drive slowly and carefully.