Besides, she didn't have time for them now. She had to think about getting back to Luna City. She would get into her crawler and away from here as quickly as possible.

Turning, she shuffled to the airlock, stepped into and through it, and out onto the lunar surface. Sweeping her helmet's lamp in wide arcs, she searched for the crawlers that should have been there-both her own and Hyatt's. And perhaps a third crawler she had not seen before: the one belonging to the man who had killed Hyatt.

The crawlers were not there. Not even her own.

Somehow, that didn't surprise her. She had almost been expecting it.

She stood unmoving, trying to decide what to do. She couldn't wait for someone to come out for her. The only one who might do that was Clayton, and by the time he missed her, then pieced together where she had gone, her suit's air tanks would be exhausted and she would be long dead. Her only hope lay in starting for Luna City on foot.

Of course, she didn't expect to make it; it was much too great a distance. The walk back would take a full ten or twelve hours, and she had less than half a tank of air now. Still, if she could get near a well-traveled lane, she might be spotted by a passing floater. It was a slim chance, but all she had.

She thought she remembered the way her guide had come. They had approached the camp from the north. She tapped the appropriate switch with her tongue, took a bearing, then started walking.

Although she knew it would drain her suit's batteries, eventually disabling the cooling system, she left the helmet lamp on. Unlike during the crawler drive out from Luna City, she now wanted to be seen. Her life depended on someone spotting her.

She trudged through the lunar landscape, over small rises and down into impact craters. The scenery that had seemed so tranquil and beautiful only three days before, on the floater trip out from Fleet Base, was now horribly monotonous.

Soon a fog of non-thought settled down around her mind.

In less than an hour her joints ached and her legs felt as if they were made of lead. Her breath rasped in her helmet. She shouldn't have been this exhausted so soon.

Then, suddenly, she knew what was wrong. Her suit was overheating, just as she had known it eventually would.

She toggled the suit monitor on with her tongue and squinted at the display projected on the inside of the helmet visor: 46 degrees celsius! No wonder she was sweating like a pig! And the cooling unit was operating at full capacity! When it finally quit, after the headlamp had totally drained the suit's battery, the temperature would climb faster still.

She toggled the lamp off with her tongue-she shouldn't have left it on. It really wouldn't do her any good until she was nearer the traffic lanes. She had only wasted precious battery power.

But it really didn't matter; she wouldn't last much longer anyway. At the rate she was tiring, it would be less than half an hour. She was burning too many calories far too quickly, but if she stopped she would be dead. Her only chance lay in getting to one of the traffic lanes between the mining camp and Luna City.

She plodded on, mechanically placing one foot before the other. After a while, the fact that she was literally cooking inside her suit no longer mattered.

She had been watching the floater for a long time before its presence actually registered in her mind. By the time she realized what she was seeing, she was in a shallow valley between low hillocks, and the horizontal pattern of green running lights was no longer visible. She clambered up the hill, losing almost as much ground as she gained with each step. She had to be visible to the floater's passengers and crew.

As she crested the hillock, she saw the floater in the distance. Now she could actually make out its outline as it glided silently toward her over the lunar surface. It would pass near-perhaps within range of her suit's radio.

But even if they couldn't receive her transmission, they would surely see her. She was in the open now, on high ground.

Suddenly, she realized her helmet lamp was off. She had turned it off some time ago to conserve the batteries.

She tongued it on, but the beam was too weak. The suit's cooling unit had drained the batteries.

She waved her arms frantically over her head, but she knew that would do little good. She shook her head from side to side, hoping at least one of the floater's passengers was looking in her direction and would see the weak helmet beam. That was her only chance.

Tonguing the radio on, she screamed into the helmet. "Here! Over here! I need help!" But batteries that no longer held enough charge to produce a strong beam from the helmet lamp could not drive the radio with sufficient power to raise the floater.

A high frequency beep started in her helmet speaker, and for an instant she thought it was the floater signaling her. Then she realized it was the suit overheat warning, and instantly digits painted on her helmet visor. The temperature was climbing past 66 degrees.

She didn't care. They would see her-they had to see her. Soon she would be safe onboard the floater, headed back to Luna City.

The floater came silently on.

They must have seen her by now, she thought. Someone onboard that floater had to be looking at his viewscreen…

A sudden chill slithered up Susan's spine as she tapped the chronometer switch with her tongue: 0912. She tapped it again to display the date on her helmet visor: Oct. 4, 2187.

Her breath caught in her lungs. The fourth was three days ago. That was the day she had left Fleet Base for Luna City-on a floater!

She remembered a dim light atop a low hill. Of course she was being seen from that floater. At least one person onboard was watching her. And that passenger would do absolutely nothing.

Tears welled up in her eyes, stinging hot as they coursed down her cheeks. The floater would not stop. Three days ago, she hadn't reported the spot of light she had thought she'd seen.

She walked slowly down the hillock. The floater passed its closest point of approach and she turned off her helmet lamp, then followed after it.

She walked for hours, mechanically putting one foot in front of the other. Occasionally, she wondered why she was walking. There was no one out on the lunar surface to find her. No one knew she had gone to the mining camp. She hadn't-not yet. There was another Susan Tanner in Luna City, being briefed by a nervous lieutenant this very minute. A Susan totally unaware of what awaited her.

Or was there? Did Susan's existence out on the surface somehow negate that other's existence in Luna City?

Somehow, she didn't think so. It just didn't feel right. That other Susan belonged in this time. She had a right to exist here-now. She was the one out of place, out of time.

Besides, she had existed then, so that other Susan existed now.

But what would happen if she somehow returned to Luna City and encountered that other? Could it even happen? And if not, might that mean she could not return to Luna City, that she was doomed to a slow death on the lunar surface?

She didn't know. She didn't really want to know.

Again she blanked her mind, and walked on.

Gradually, she realized she was having trouble breathing. Willing her diaphragm to work, she took a deep breath. It did no good. She tried again, attempting to force air into her lungs. Then again. Suddenly, she was hyperventilating.