usan sat alone in Node 3, waiting for her tracer. Hale haddecided to step outside and get some air—a decision for whichshe was grateful. Oddly, however, the solitude in Node 3 providedlittle asylum. Susan found herself struggling with the newconnection between Tankado and Hale.

"Who will guard the guards?" she said to herself. Quis custodiet ipsos custodes. The words kept circling in herhead. Susan forced them from her mind.

Her thoughts turned to David, hoping he was all right. She stillfound it hard to believe he was in Spain. The sooner they found thepass-keys and ended this, the better.

Susan had lost track of how long she'd been sitting therewaiting for her tracer. Two hours? Three? She gazed out at thedeserted Crypto floor and wished her terminal would beep. There wasonly silence. The late-summer sun had set. Overhead, the automaticfluorescents had kicked on. Susan sensed time was running out.

She looked down at her tracer and frowned. "Come on,"she grumbled. "You've had plenty of time." Shepalmed her mouse and clicked her way into her tracer's statuswindow. "How long have you been running, anyway?"

Susan opened the tracer's status window—a digitalclock much like the one on TRANSLTR; it displayed the hours andminutes her tracer had been running. Susan gazed at the monitorexpecting to see a readout of hours and minutes. But she sawsomething else entirely. What she saw stopped the blood in herveins.

TRACER ABORTED

"Tracer aborted!" she choked aloud."Why?"

In a sudden panic, Susan scrolled wildly through the data,searching the programming for any commands that might have told thetracer to abort. But her search went in vain. It appeared hertracer had stopped all by itself. Susan knew this could mean onlyone thing—her tracer had developed a bug.

Susan considered "bugs" the most maddening asset ofcomputer programming. Because computers followed a scrupulouslyprecise order of operations, the most minuscule programming errorsoften had crippling effects. Simple syntactical errors—such asa programmer mistakenly inserting a comma instead of aperiod—could bring entire systems to their knees. Susan hadalways thought the term "bug" had an amusing origin:

It came from the world's first computer—the Mark1—a room-size maze of electromechanical circuits built in 1944in a lab at Harvard University. The computer developed a glitch oneday, and no one was able to locate the cause. After hours ofsearching, a lab assistant finally spotted the problem. It seemed amoth had landed on one of the computer's circuit boards andshorted it out. From that moment on, computer glitches werereferred to as bugs.

"I don't have time for this," Susan cursed.

Finding a bug in a program was a process that could take days.Thousands of lines of programming needed to be searched to find atiny error—it was like inspecting an encyclopedia for a singletypo.

Susan knew she had only one choice—to send her traceragain. She also knew the tracer was almost guaranteed to hit thesame bug and abort all over again. Debugging the tracer would taketime, time she and the commander didn't have.

But as Susan stared at her tracer, wondering what errorshe'd made, she realized something didn't make sense. Shehad used this exact same tracer last month with no problems at all.Why would it develop a glitch all of a sudden?

As she puzzled, a comment Strathmore made earlier echoed in hermind. Susan, I tried to send the tracer myself, but the data itreturned was nonsensical.

Susan heard the words again. The data it returned…

She cocked her head. Was it possible? The data it returned?

If Strathmore had received data back from the tracer, then itobviously was working. His data was nonsensical, Susan assumed,because he had entered the wrong search strings—butnonetheless, the tracer was working.

Susan immediately realized that there was one other possibleexplanation for why her tracer aborted. Internal programming flawswere not the only reasons programs glitched; sometimes there wereexternal forces—power surges, dust particles on circuitboards, faulty cabling. Because the hardware in Node 3 was so welltuned, she hadn't even considered it.

Susan stood and strode quickly across Node 3 to a largebookshelf of technical manuals. She grabbed a spiral binder markedSYS-OP and thumbed through. She found what she was looking for,carried the manual back to her terminal, and typed a few commands.Then she waited while the computer raced through a list of commandsexecuted in the past three hours. She hoped the search would turnup some sort of external interrupt—an abort command generatedby a faulty power supply or defective chip.

Moments later Susan's terminal beeped. Her pulse quickened.She held her breath and studied the screen.

ERROR CODE 22

Susan felt a surge of hope. It was good news. The fact that theinquiry had found an error code meant her tracer was fine. Thetrace had apparently aborted due to an external anomaly that wasunlikely to repeat itself.

error code 22. Susan racked her memory trying to remember whatcode 22 stood for. Hardware failures were so rare in Node 3 thatshe couldn't remember the numerical codings.

Susan flipped through the SYS-OP manual, scanning the list oferror codes.

19: CORRUPT HARD PARTITION

20: DC SPIKE

21: MEDIA FAILURE

When she reached number 22, she stopped and stared a longmoment. Baffled, she double-checked her monitor.

ERROR CODE 22

Susan frowned and returned to the SYS-OP manual. What she sawmade no sense. The explanation simply read:

22: MANUAL ABORT