… SPENCE SNAPPED THE SEAL and unrolled the strip to the beginning, watching meters and meters of paper tape unwind through his fingers. At the start of the tape he saw the date and time notation: EST 5/15/42 10:17 GM. The scan continued for nine and three-quarter hours without interruption. Each peak and every valley, every blip of an alpha spark or beta flash was duly recorded. He saw the minute fluctuations in cerebral blood flow; the rise and fall of body temperature, heart rate, and thyroid activity; the intermittent REM flutters. He saw, in short, the even, rhythmic progress of his night's sleep. His every moment was accounted for. Undeniably so-he held the evidence in his own hands.

But it was not enough. He turned to the cabinet where all the spools were kept. There were dozens of them, each one containing the polysomnographic information of one night's sleep session. He lifted the row containing the scans of the last week. He checked each one. They were all there, labeled and sealed correctly.

He checked the week before that and the next one, too. All was in order. Tickler was as precise as he was stuffy. Spence knew that if he looked at every spool over the last ten weeks he would find them in order. Still, a small gray shadow of doubt clung to his mind.

He turned once more to the scan he had unrolled-the one from the night of his first blackout three days ago. He pulled the tape through his hands and examined it closely. It was no different from all the others.

He spied the yellow plastic cover of the log book on the corner of the console and pulled it to him. On top of the log book lay a piece of green graph paper on which was plotted the averages Spence had requested for the last three sessions. Kurt must have come in and finished it while he was out. He glanced at the graph of the averages and then opened the log book and traced up the columns to the session of the fifteenth. He found no irregularities in any of the figures or information. He closed the book with the sinking feeling that all was in order and only he was out of sync.

He threw the book down on the console and leaned back with his hands clasped behind his head. If an answer existed to his problems it would have to exist in some form in the hard data before him. Somewhere in the miles of tape, or in the figures in the book, the key to the locked room of his mind could be found. Of that he was certain. His faith in the scientific method stood on solid, unshakable rock.

On a whim he swiveled to the data screen at one end of the console. The wafer-thin, half-silvered glass shone smooth as polished stone. "MIRA," said Spence, "Spence Reston here. Ready for command."

A mellifluous female voice said, "Ready, Dr. Reston," Spence uttered the simple command: "Compare entries for PSG Seven Series LTST five-fifteen to five-eighteen for similarties. Display only, please."

He laced his fingers behind his head and leaned back in his chair. Instantly the wafer screen flashed to life and the results began filling the screen. It seemed there were many similarities between one night's scan and the next in terms of basic numerical components. All of the information gathered during a scanning session was translated into numbers for purposes of data storage and retrieval. They were all alike in many ways, and yet all different.

The command was too broad. That much he could see, but he did not know how to narrow the question because he did not know precisely what he was looking for. He crossed his arms over his chest and frowned at the screen. Just what did he hope to find?

After several minutes of hard thought he stood and began pacing the cramped confines of the booth. Compare and contrast, he thought. That's where you start on a fishing expedition of this type. Compare and contrast.

He had already compared and that had not shown him anything out of the ordinary. Perhaps contrasting the same information would produce something. He turned to the screen and said, "Contrast PSG LTST entries for five-fifteen to five-eighteen. Display only, please."

The numbers vanished and in their place the screen began printing: Zero contrast within normal range of variability ± 3%. In other words, dead end.

Spence glanced at the digiton above the console. In a few minutes Tickler would arrive to begin the session. He did not want Tickler to find him here like this playing detective. A silly thought he knew-1 have a perfect right to examine the data of my own experiment, for goodness sakes-but he preferred that Tickler should know nothing about his inquiry.

Judging he had time for two more stabs in the dark, he said, "Compare PSG LTST Seven Series entries five-fifteen to five-eighteen for similarities of less than one percent variability. Display only, please." He nodded with satisfaction; by decreasing the percentage of variability he had narrowed the question significantly.

In moments MIRA came back with its findings. The message read: Zero comparison. Spence frowned again. There were apparently no great similarities or differences in any of the scans – beyond the normal range of his individual sleep pattern.

With a sigh he kicked back his chair. This kind of blind fumbling was useless. Unless he knew what he hoped to discover, no amount of random searching would help. "Thank you, MIRA. That is all for…"

He stopped in mid-sentence. It occurred to him that he had not compared all of the scans, only those from the fifteenth to the eighteenth-the two dates encompassing his blackouts.

"MIRA, compare all PSG LTST Seven Series entries. Display entries with similarities of less than one percent variability."

There was a slight hesitation; the wafer screen went blank. He imagined he could hear the chips crackling with speeding electrons as MIRA wracked her magnetic memory.

Spence sat on the edge of his chair and watched the clock tick away the seconds. Any moment Tickler would come walking in. Hurry! Spence muttered. Hurry!

Then the words appeared. He read the message as it came up: PSG LTST Seven Series entries with less than 1% variability = 3/20 and 5/15.

Jackpot! Spence jumped out of his chair and stared at the screen in disbelief. There it was; an anomaly too large to exist, its very presence an impossibility. If he had discovered it any other way he would have chalked it up to a computer glitch. But he had a strong suspicion that it was no glitch. He had uncovered a vital bit of information-stumbled blindly over it, more like-but there, spelled out in fluorescent orange, was the evidence.

He picked up the yellow log book and paged through to the entry of 3/20. He pulled the sheet and placed it next to the entry of 5/15. They were not at all similar. Each entry in Tickler's neat, precise hand was slightly different-not enough to vary a great deal, but enough for Spence to see that they were both unique.

Apparently, MIRA had glitched after all. There was no similarity between the two scans.

Spence heard the swoosh of the panel opening and Tickler's quick footsteps entering the lab. He said, "That is all, MIRA. Thank you."

"Good evening, Dr. Reston."

"Good evening, Tickler." Spence turned and forced what he hoped was a casual smile.

"Are we ready to begin our session?" Tickler's small, weasel eyes glanced from Spence to the wafer screen above the terminal.

"Oh, I meant to tell you about that. I am canceling the session this evening." Spence surprised himself with that announcement.

"I don't understand, sir. I've prepared everything-we're all ready. If you-"

"Never mind. It can wait. I have something else for you to do tonight. You and Kurt, that is. I want you to run averages for the last two weeks. I think a curve may emerge that we may want to explore. That should take you most of the session, I think."