HAD THE VISITOR BEEN A MAN, HE WOULD HAVE knocked. If it had been only the wind, it would have huffed and strained against the door until the planks creaked.

This scrape was the sound of bone on wood, or something like bone. I could imagine an animated skeleton clawing with mindless persistence at the other side of the door.

In all my bizarre experiences, I had never actually encountered an animated skeleton. But in a world where McDonald's now sells salads with low-fat dressing, anything is possible.

The reception lounge was deserted. Had it been staffed, only a nun or two would have been there, anyway.

If something like what I had glimpsed in the storm was able to break the door off its hinges, I would have preferred better backup than the average nun could provide. I needed someone even tougher than Sister Angela with her penetrating periwinkle stare.

The doorknob rattled, rattled, turned.

Doubtful that my resistance alone would keep out this unwanted caller, I engaged the dead-bolt lock.

A scene from an old movie played in my memory: a man standing with his back pressed to a stout oak door, believing himself to be safe from preternatural forces on the farther side.

The film had been about the evils of nuclear energy, about how minimal exposure to radiation will overnight cause ordinary creatures to mutate into monsters and to grow gigantic as well. As we know, in the real world, this has had a devastating impact on the real-estate values in the monster-plagued communities near all of our nuclear power plants.

Anyway, the guy is standing with his back to the door, feeling safe, when a giant stinger, curved like a rhino horn, pierces the oak. It bursts through his chest, exploding his heart.

The monsters in this flick were only marginally more convincing than the actors, on a par with sock puppets, but the skewering-stinger scene stuck in my mind.

Now I stepped away from the door. Watched the knob rattling back and forth. Eased farther away.

I had seen movies in which one kind of fool or another, putting his face to a window to scope the territory, gets shotgunned or gets seized by a creature that doesn't need a gun and that smashes through the glass and drags him screaming into the night. Nevertheless, I went to the window beside the door.

If I lived my entire life according to movie wisdom, I would risk winding up as spinning-eyed crazy as do many of our nation's most successful actors.

Besides, this wasn't a night scene. This was a morning scene, and snow was falling, so probably the worst that would happen, if life imitated films, would be someone breaking into "White Christmas" or the equivalent.

A thin crust of ice had crystallized across the exterior of the windowpanes. I detected something moving outside, but it was no more than a white blur, an amorphous shape, a pallid form quivering with potential.

Squinting, I put my nose to the cold glass.

To my left, the knob ceased rattling.

I held my breath for a moment to avoid further clouding the window with every exhalation.

The visitor on the doorstep surged forward and bumped against the glass, as if peering in at me.

I twitched but did not reel back. Curiosity transfixed me.

The opaque glass still masked the visitor even as it pressed forward insistently. In spite of the obscuring ice, if this had been a face before me, I should have seen at least the hollows of eyes and something that might have been a mouth, but I did not.

What I did see, I could not understand. Again, the impression was of bones, but not the bones of any animal known to me. Longer and broader than fingers, they were lined up like piano keys, although they were not in straight keyboards, but were serpentine, and curved through other undulant rows of bones. They appeared to be joined by a variety of knuckles and sockets that I observed, in spite of the veil of ice, were of extraordinary design.

This macabre collage, which filled the window from side to side, from sill to header, abruptly flexed. With a soft click-and-rattle like a thousand tumbling dice on a felt-lined craps table, all the elements shifted as if they were fragments in a kaleidoscope, forming a new pattern more amazing than the previous.

I leaned back from the window just far enough to be able to appreciate the entire elaborate mosaic, which had both a cold beauty and a fearsome quality.

The joints that linked these ranked rows of bones-if bones they were, and not insectile limbs sheathed in chitin-evidently permitted 360-degree rotation along more than one plane of movement.

With the dice-on-felt sound, the kaleidoscope shifted, producing another intricate pattern as eerily beautiful as the one before it, though a degree more menacing.

I got the distinct feeling that the joints between the bones allowed universal rotation on numerous if not infinite planes, which was not just biologically impossible but mechanically impossible.

Perhaps to taunt me, the spectacle remade itself once more.

Yes, I have seen the dead, the tragic dead and the foolish dead, the dead who linger in hatred and the dead who are chained to this world by love, and they are different from one another yet all the same, the same in that they cannot accept the truth of their place in the vertical of sacred order, cannot move in any direction from this place, neither to glory nor to an eternal void.

And I have seen bodachs, whatever they may be. I have more than one theory about them but not a single fact to support a theory.

Ghosts and bodachs are the sum of it. I do not see fairyfolk or elves, neither gremlins nor goblins, neither dryads nor nymphs, nor pixies, neither vampires nor werewolves. A long time ago, I stopped keeping an eye out for Santa Claus on Christmas Eve because, when I was five, my mother told me that Santa was a wicked pervert who would cut off my peepee with a pair of scissors and that if I didn't stop chattering about him, he would be certain to put me on his list and look me up.

Christmas was never the same after that, but at least I still have my peepee.

Although my experience with supernatural presences had been limited to the dead and bodachs, the thing pressed to the window seemed more supernatural than real. I had no idea what it might be, but I was reasonably confident that the words fiend and demon were more applicable than the word angel.

Whatever it was, thing of bone or thing of ectoplasm, it had something to do with the threat of violence that hung over the nuns and the children in their charge. I didn't have to be Sherlock Holmes to figure that out.

Apparently each time the bones shifted, they abraded the ice and shaved some off the glass, for this mosaic was clearer than those that had preceded it, the edges of the bones sharper, the details of the joints slightly more defined.

Seeking a better understanding of the apparition, I leaned close to the glass again, studying the disturbing details of this unearthly osteography.

Nothing supernatural has ever harmed me. My wounds and losses have all been at the hands of human beings, some in porkpie hats but most dressed otherwise.

None of the many elements in the bony mosaic trembled, but I had an impression that it was tight with tension.

Although my breath bloomed directly against the window, the surface did not cloud, most likely because my exhalations remained shallow, expelled with little force.

I had the disturbing thought, however, that my breath was without warmth, too frigid to cloud the glass, and that I inhaled darkness with the air but breathed no darkness out, which was a strange notion even for me.

I stripped off my gloves, shoved them in my jacket pockets, and placed one hand lightly on the cold glass.