There was, on the slender bole of the youthful maple tree in its cage on the west side of Union Square, an enormous moth. It rested, papillating its wings with a certain languor like a lady fanning herself, iridescent green with a yellowish undershimmer, as big as that languid lady's silk clutch. Its wings lay spread flat and when, every so often, they pulsed, the woman in the checked coat would squeal, to the amusement of the others gathered around, and jump back.

"What is this moth?" Joe asked the man beside him.

"Guy here says it's called a luna." The man nodded toward a stout, bankerish-looking fellow in a tyrolean hat with a moth-green feather, standing nearer to the tree and the moth than any of them.

"That's right," the portly man said in an oddly wistful voice. "A luna moth. We used to see them from time to time when I was a kid. In Mount Morris Park." He reached out his pudgy hand, in its yellow pigskin glove, toward the beating blue heart of his childhood memory.

" Rosa," Joe said, under his breath. Then, like an ambiguous trope of hopefulness, the luna moth took wing with an audible rustle, tumbled upward into the open sky, and staggered off in the general direction of the Flatiron Building.

So much has been written and sung about the bright lights and ballrooms of Empire City-that dazzling town!-about her nightclubs and jazz joints, her avenues of neon and chrome, and her swank hotels, their rooftop tea gardens strung in the summertime with paper lanterns. On this steely autumn afternoon, however, our destination is a place a long way from the horns and the hoohah. Tonight we are going down, under the ground, to a room that lies far beneath the high heels and the jackhammers, lower than the rats and the legendary alligators, lower even than the bones of Algonquins and dire wolves-to Office 99, a small, neat cubicle, airless and white, at the end of a corridor in the third subbasement of the Empire City Public Library. Here, at a desk that lies deeper in the earth than even the subway tracks, sits young Miss Judy Dark, Under-Assistant Cataloguer of Decommissioned Volumes. The nameplate on her desk so identifies her. She is a thin, pale thing, in a plain gray suit, and life is clearly passing her by. Twice a week a man with skin the color of boiled newspaper comes by her office to cart away the books that she has officially pronounced dead. Every ten minutes or so her walls are shaken by the thunder of the uptown local racing overhead.

On this particular autumn night, only the prospect of another solitary evening lies before her. She will fry her chop and read herself to sleep, no doubt with a tale of wizardry and romance. Then, in dreams that strike even her as trite, Miss Dark will go adventuring in chain mail and silk. Tomorrow morning she will wake up alone, and do it all again. Poor Judy Dark! Poor little librarians of the world, those girls, secretly lovely, their looks marred forever by the cruelty of a pair of big black eyeglasses!

Judy packs her satchel and turns out her light, not forgetting to take her umbrella from its hook. She is a kind of human umbrella, folded, with her strap snapped tight. She walks down the long corridor and accidentally steps into a huge puddle; whenever it rains, Subbasement 3 begins to leak. Her feet are soaked to the ankles. Shoes squeaking, she gets into the elevator. Like a diver, she rises slowly to the surface of the city. Turning up her collar, she heads for the front door of the library. Tonight, as every night, she is the last to leave.

There is a policeman by the front doors. He is there to help guard the book.

"Good night, Miss," the policeman says as he unlocks the heavy bronze door for her. He is a big-shouldered, knuckle-chinned fellow with a twinkle in his eye because her shoes are squeaking.

"Good night." Miss Dark is mortified by the sound of her feet.

"The name's O'Hara." He has thick, shining hair, glossy as a squirt of black paint.

"Judy Dark."

"Well, Miss Dark, I have just one question."

"Yes, Officer O'Hara?"

"What's it take to get a smile out of you?"

A dozen smart retorts spring to her lips but she says nothing. She tries fervently to fix a frown on her lips but to her dismay cannot prevent herself from smiling. O'Hara takes advantage of her confusion to keep her there talking for a moment longer.

"Did you have a chance to see the book in all the confusion today, Miss Dark? Would you like me to show it to you?"

"I saw it," she says.

"And what did you think?"

"It's lovely."

"Lovely," he tries. "Is it, now?"

She nods, not meeting his gaze, and steps out into the evening. It is raining, of course. The umbrella now does what its owner has never been able to manage, and Miss Dark goes home. She fries her veal chop and turns on the radio. She eats her dinner and wonders why she lied to the policeman. She has not, in fact, been to see the Book of Lo, though she is dying to see it. She meant to go on her lunch break, but the crowd around its case was too big. She wonders what the book is, if not lovely.

The Book of Lo was the sacred book of the ancient and mysterious Cimmerians. Last year-as was widely reported at the time-this legendary text, long since given up for lost, turned up in the back room of an old wine cellar downtown. It is the oldest book in the world, three hundred ancient pages, in a leather case encrusted with rubies, diamonds, and emeralds, devoted to the strange particulars of the worship of the great Cimmerian moth goddess, Lo. Today it went on display in the grand exhibition hail of the Public Library, behind bulletproof glass. Half the city, it seemed, came to get a look. Miss Dark, driven away by the pushing crowds, returned to Office 99 without having gotten so much as a glimpse of it and ate her lunch at her desk. Now, looking up from her empty plate, at the walls of her empty apartment, she feels a sharp inward bite of regret. She ought to have taken the policeman up on his offer. Maybe, she thinks, it isn't too late. She puts on her hat and coat and a pair of dry shoes and heads back out into the night. She will tell Officer O'Hara, when she gets there, that there is work she has forgotten to do.

But when she gets there, Officer O'Hara seems to have abandoned his post, and what's more, he has left the front door unlocked. Curious, and vaguely annoyed-suppose someone really should try to steal the Book of Lo?-she wanders into the exhibit hall. There, on the black marble expanse of the floor, men in black masks stand around the fallen body of Officer O'Hara. Miss Dark ducks behind a convenient arras. She thrills with horror as the men-an apelike trio in stevedore sweaters and newsdealer caps-use a diamond-tipped can opener to slice the lid from the glass case and so relieve Empire City of its book. Hastily they stuff the book into a sack. Now: what about O'Hara? One of the thieves knows for sure, he says, that the copper made him; he and O'Hara grew up on the same block, way back when. Maybe they had better just do the poor sap in.

This is too much for the Under-Assistant Cataloguer of Decommissioned Volumes. She rushes into the echoing hall with a vague plan to frighten or at the very least distract the men from their evil work. Or perhaps she can lead them away by drawing their attention to herself. Taking advantage of the momentary confusion created by her appearance and her cry of "NOOOOOO!" she snatches up the sack with the sacred Book of Lo inside and runs out of the gallery. The thieves, having recovered their presence of mind, give chase now, guns drawn, curses streaming from their lips in mad torrents of printer's marks and random punctuation.

Miss Dark, terrified but not so that it prevents her from entertaining the ironic thought that for the first time in her life she knows what it feels like to have men chasing after her, heads for the safest place she knows: her neat, square hole underground. She cannot afford to wait for the elevator. Running headlong down the fire stairs she is struck by the odd feeling that the Book of Lo has come to pulsing life in her arms; but no, that's just the reverberation of her own pounding heart.