Sisshain.

"It's still a tossup," Barton said.

"What's his estimated lead now?" said Alene.

"Only about a light-minute, maybe a little over. But our rate of approach is dropping off, damn it! On decel, our exponential curve has a negative exponent."

"Barton, look!" said Eeshta. "What is happening?"

The Hishtoo dot now maintained constant distance from its pursuer.

"He's speeded up!" Alene.

"Reduced decel, you mean," said Barton. "But why?"

Abdul had entered unnoticed; now he spoke. "He has dropped below light speed, and now detects us. I- will obtain a readout of the exact time and coordinates. What can be done?"

"Two can play." Barton's grin was tight. "Back off decel, Alene. Back off until we start closing again." .

"But what if-? Barton, we'll overrun Sisshain'"

"Do it. If we overrun, so does Hishtoo-he can't land, either. And he can't keep too much speed, or he won't be able to turn inside the limits of the dust cloud. We have the bulge on him in turning radius, too." He slammed a fist into his other palm. "If only the other ships were in talk range!"

Of them all, Abdul showed no excitement. "What would you wish to do?"

Barton wheeled from the board, faced him. "We could chase Hishtoo to the limit where we could land and he couldn't. Then the others could bag him."

"They might, anyway," said Alene. "But you're for- getting something."

Barton exhaled, shrugged. "I wouldn't be surprised- it happens all the time. Now what?"

"According to Vertan, once Hishtoo is this close to Sisshain, he doesn't have the fuel to go anywhere else."

284.

"Grover, I love you!" In jubilation, he hugged her.

"Go get 'em, kid!"

"He pulls away more rapidly," said Abdul. "How-?"

"He's made turnover again," Barton said. "Match him, Alene! Not turnover-just slack hell out of your decel." Again, the two dots approached each other.

"You have all forgotten something," said Eeshta.

"Hishtoo need not land. He need only speak with Sisshain, and perhaps more ships will rise from there, to warn the Demmon sector, than you can intercept."

"If I catch up with him, he won't be speaking to any- body!"

"But," said Abdul, "I thought you did not wish to kill the hostages. Of course, if it is necessary . . . . "

"Burning off his antenna systems won't kill anybody."

"Barton," said Alene, "he's slowing again. Fast!"

"Another turnover? Wants us to overrun him, meet and pass too fast for any action. Or else he passed light speed, lost us again, and panicked. Whatever-just match him, is all."

She tried, but Hishtoo reversed his action, and then again. And with each move, the Demu increased either the distance or the relative velocity between the ships.

"This method-matching his moves after the fact- will not be effective," said Abdul. "He has the initiative;

he is acting, while we can only react, too late."

"I never said he was stupid," said Barton. "You got any suggestions?"

"May I take the pilot's seat? What I have in mind is easier to do than to explain. No reflection, Alene Grover, on your abilities. Under a great disadvantage, you have done well."

"No offense at all, Abdul. I'm a good Jet-jock if I do say so, but you can make that computer do tricks I never heard of." They changed places; as he watched the screen, Abdul began running simulations.

"You guessed then, Alene. I too am limited to reacting to received data-but I am responding not to Hishtoo's moves as shown directly on the screen, but to a com- puter prediction, in real time, of his response to my next change, on the basis of his earlier actions.

"I will lose ground-rather, I did lose ground-you see it, here?-on the first move, for it had to be made arbitrarily, to establish a baseline. But now we are work-

285.

ing with a converging series and should soon begin to gain appreciably."

And it worked. Barton saw-sure as hell, it worked.

First slowly, then more rapidly, Abdul recouped from Hishtoo his advantages of distance and speed-differential.

The dot that showed the Demu's ship darted frantically.

"He now makes changes at random, I believe," said Abdul. "That method will not help him-his actions cancel each other, and the computer can work with trends as well as with individual moves." The dot sub- sided to a slow, steady drift.

"He's not doing anything," Alene said. "What's hap- pened?"

Abdul consulted the screen, checked a tape readout.

"He has established a constant deceleration that will bring him to rest at Sisshain. I will set course to intercept at soonest."

"I don't understand," said Alene. "Has he given up?"

Barton shook his head. "He hasn't quit-not Hishtoo.

It's just that he can't do it with his ship, so now he'll do it with the hostages." His face took on the feel of weathered rock. "Or so he thinks. I'm sorry, Eeshta- sorry for all of them, and for us."

Eeshta spoke. "When do we come to meet with Hishtoo?"

"If he makes no change-" said Abdul. "-Wait, let me try a variation." For nearly two silent minutes he ran calculations. "We both are off the original course, and thus at a lower velocity than before, toward Sisshain itself. His present-and optimum-deceleration is now considerably less than our own capability. Barton- may I suggest?"

"May? Hell, it's an order!"

"What? Oh, I see." Abdul's smile was broad. "Very well-on straight deceleration we would reach Hishtoo in approximately thirty hours. At that time he may be within communication range to Sisshain. I presume we do not wish that to occur."