He faced Fleta. "In fact, your horn does sound like the croaking of frogs," he said loudly. "Beautiful!"

Fleta smiled. "I thank thee for that compliment."

The frogs considered that. Then the leader jumped into the pond. After that the others followed. In a moment the mud was clear.

"I think they have forgiven thee," Fleta murmured. Then she embraced him and kissed him, in the midst of her laughter.

She changed back to 'corn form and played a new melody. This time Mach joined her, singing counterpoint. And from the pond the croaking resumed, providing a melodic background. It was as though an entire orchestra were performing.

There was a rumble. The ground shook. Fleta stopped playing, alarmed.

The pond abruptly drained away, its water disappearing into the ground beneath. The frogs scrambled desperately to escape. The mud bubbled and slid into the deepening hole.

The flower garden caved in around them. Fleta blew a startled note, bracing her four feet. Mach, realizing that something was seriously amiss, leaped for her, scrambling to her back as his footing gave way. "Get out of here!" he cried.

She leaped-but the entire garden collapsed under her hooves, dropping them down into a forming sinkhole. Fleta kept her feet, but slid to the bottom.

Now smoke showed, issuing from forming vents. "It's a caldera!" Mach cried, jumping off her back. "Change to bird form and fly out, Fleta!"

But she did not; she would not leave him in this danger.

The ground shook again, and the volume of smoke increased, obscuring everything. It seemed to form a globe about them, closing in.

"Magic!" Mach cried. "I'll try a spell!"

But in this pressure of the moment, he could think of neither rhyme nor melody. Fleta blew a note, trying to help him, but then the smoke closed in, chokingly, and they were helpless.

In a moment, it cleared-but they were no longer in the garden. They were in a chamber hewn from rock- and great ugly creatures surrounded them. The creatures pounced, grasping Mach by the arms, one of them clapping a rough and dirty hand over his mouth. Others flung themselves on Fleta, shoving her against the wall while one grasped her horn.

"Welcome, apprentice!" a man said, entering the chamber. "I am the Purple Adept, and these trolls be under my sway. As thou mayst know, I reside in the Purple Mountains, and I possess the magic of the movements of the earth. Now I want thy cooperation, apprentice, and I want thy word on that now."

At a signal from Purple, the troll removed his hand from Mach's mouth. Mach spat out gravel. "I'll give you no such word, criminal!"

"Now I know thou canst not do magic without thy mouth, and my minion will clap his hand back o'er it the moment thou dost try to sing a spell. So thou canst not escape by thy magic."

"But I won't help you, either!" Mach said.

"But an thee give me not thy word, it will go grievously with thy steed here."

"She's not my steed!" Mach exclaimed.

"Aye, she be thy concubine. I saw as much when the two of you trespa.s.sed across my Demesnes. Now I ask thee, apprentice: how much music will that mare play, without her horn?"

Fleta renewed her struggles, but the ma.s.s of trolls overwhelmed her. She could neither escape nor change form, while her horn was held.

What would happen to a unicorn whose horn was amputated? Mach didn't know, but the very fact that the evil Adept expected him to be cowed by this threat served the purpose. He had no faith in any good will by this man, and he couldn't risk harm to Fleta.

"I will carry a message to Proton," he said dully. "Release Fleta."

"Release her? Nay, she will remain with us-unharmed pending thy cooperation." The Purple Adept made another signal, and the trolls heaved and shoved the resisting unicorn from the chamber. "She will reside in an enchanted cell that be proof from her escape in any form. An thou cooperate fully, she will be well enough treated otherwise."

Mach felt a private rage such as he had never experienced when he had been a robot, but he knew he had to control it. He just could not risk harm to Fleta! "What is your message?"

'The first one will be to mine other self, Citizen Purple, just to let him know that contact has been reestablished. He will know what to do, and what message to return."

The first one. When would this brute ever give over? Not as long as he had control of Fleta!

But perhaps there was a way out. Mach suppressed that thought, not wanting any hint of it to show here. "I have to overlap the spot my other self occupies," he said. "I can't do that if you don't let me move about."

"Thou shalt move about-in my presence," Purple said. "And be thou advised, apprentice, that thy magic may be apt against ordinary folk, but cannot compare with mine own. An thou try something against me, not only will I balk it, I will let my minions at the animal's horn. Trolls hate 'corns; only the restraint I impose prevents them from making her scream."

There will be a reckoning, Mach thought, then quelled his outrage.

He tuned in on Bane-and his other self was very close now. Apparently Bane had been able to follow him here. So it would happen soon-and then he would see whether his wild notion would work.

He experimented, discovering that he could tell the direction from which his other self was coming. He faced that way, ready to walk toward Bane-but he was in a tunnel underground, and the rock wall cut him off.

So he walked along the tunnel, angling toward the other self, while the Purple Adept paced him. "As I understand this," Purple said, "thou art from Proton and have little power of magic. When thou dost exchange back, Bane will be here, and he has power. But thou must remember that any hostile magic practiced here will cost the horn of the animal, and perhaps more thereafter. So thou wouldst be best advised to deliver the message, and bring the return message-and to advise thine other self of the wisdom of this procedure. He may not care for the animal as thou dost, and will leave her to her fate otherwise."

"Understood," Mach said tightly. He kept walking.

The awareness of his other self grew steadily stronger. Mach realized that the two would overlap very soon. He resolved to accomplish the exchange without giving any outward sign. That was part of his wild plan.

The tunnel curved, allowing him to proceed directly toward his target-and suddenly it happened. Overlap! But Mach did not stop walking, and in a moment the contact slipped; he had not grasped the opportunity when it had come.

Then he felt his other self approaching from behind. Wait, it thought.

I cannot, Mach thought back, as the other paced him for a moment. I am in enemy power.

So am I, the other returned.

Mach quailed. His wild hope had been dashed. He had wanted to get help through Proton, arranging some counter pressure there that would nullify the hold Purple had oh him. If he could have made the exchange without Purple knowing, and arrange the counter-action, and exchanged back- He kept walking, and the other phased in again, this time maintaining it. Fleta is hostage; I am helpless.

Agape be hostage here.

Quickly they compared situations-and realized that they had a chance after all. Satisfied, they made the exchange.

Mach found himself in the same tunnel, only now it was a pa.s.sage, lighted by electricity instead of magic-glow. He was naked. The one who paced him now was Citizen Purple, a man he knew by reputation. Obviously he had taken Agape hostage in much the same fashion as his other self, the Purple Adept, had taken Fleta hostage. And Bane must have developed a close relationship with the alien female. Well, it was perhaps no stranger than his own with Fleta.

He turned to the Citizen. "Contact be near, now," he said. "What be thy message, again?" He hoped he had the language down well enough to fool the man.

"Stop stalling, boy!" Purple snapped. "You know the message!"

Mach stopped walking. "Let me see her again."

"You aren't in any position to bargain!" the Citizen said.

"An what if I go-an thou hast dispatched her already? Must I needs know she be well, now."

Purple grimaced. "You push your luck, machine. This one stall I will allow; then you will do it, or see her in the pot."

In the pot? What could that mean?

They took a side pa.s.sage, and came to the cell where Agape was confined. "Let me go in with her," Mach said.

"It's your last d.a.m.ned smooch; make it a good one," Purple said.

The serf guard let Mach in. Agape stood to meet him. "Bane! Didn't it work?"

He took her in his arms. He had not realized what a luscious creature she was! It was evident that she had learned much about human interaction since his brief contact with her.

He kissed her-and felt her stiffen. She realized that something was wrong. But before she could speak, he put his lips to her ear and whispered, "I am Mach. Give no hint. Melt your way out at night, go to the nearest maintenance service outlet, and tap this pattern." He clicked his teeth three times quickly, then three times slowly, then three times quickly again, in the ancient SOS signal he had discovered when researching for a game. He had set it up as a code to the self-willed machines: one that only he would think to send.

'Then trust the machines; they will get you out. Tell Citizen Blue. I will try to distract attention from your cell tonight."

He kissed her again, then separated. "An I see thee not again, think kindly of me," he said, loudly enough for others to hear.

"Oh, you'll see her again," Purple said. "Right here, when you return with my message from Phaze."

"Thou art a hard man," Mach muttered.

They returned to the key section of the pa.s.sage. "It be very close here," Mach said. "I feel his presence."

"Well, merge!" the Citizen said impatiently.

Mach tuned in, and felt Bane approaching. He stepp up to meet him. They overlapped.

Did you do it? Mach thought.

Aye. And thee?

Yes.

Then it be time. Time, Mach agreed.

They separated. Mach remained in Proton; they had not tried to exchange frames this time. They had just needed the news of their success to be delayed until now. For Mach had no compelling personal reason to visit Agape, and Bane had none to visit Fleta; the enemy forces would keep the females securely isolated after the exchange. Indeed, this was the only safe policy-as the strategy he and Bane had formulated should show. Mach looked around, feigning confusion. "Where am I?" he asked.

"Proton," the Citizen replied.

"Then I am back! The exchange worked!"

"That's right, robot."

"Then I have a message for you."

"A message? But I just sent your other self with one!"

Mach smiled. "It seems your opposite number had the same notion you did. His message is this: Contact has been reestablished."

"I know that!" Purple snapped. "What else?"

"Nothing else. He said you would know what to do, and what message to return."

"That's the message I sent him!"

"Evidently great minds run in similar channels," Mach said.

"Don't get cute with me, robot!"

Mach smiled grimly. "How can I be cute with a person for whom I have no respect?"

"I'll have you dismantled and fed into the refuse recycler!" the Citizen snapped.

"And lose your only contact with Phaze? Whom do you suppose you are fooling, Purple?"

The Citizen began to a.s.sume the color of his name. "You play a dangerous game, machine."

"Listen, you idiot-this isn't Bane you're talking to! You can't deceive me the way you did him. I am the son of Citizen Blue, and Blue will grind your meaty posterior into hamburger when he finds out what you have done. How long do you think you can keep it secret?"

Purple a.s.serted some control over himself. "Do you forget that I have your alien girlfriend hostage to your cooperation?"

"What alien girlfriend? I broke up with Doris the cyborg before I went to Phaze; I have no girlfriend in this frame."

The Citizen took stock, realizing that he had lost that aspect of his leverage when Bane and Mach returned to their own frames. Then he saw his avenue. "So you do have a girlfriend in Phaze. And if I know my other self- as I surely do-he has that girl in his power. If you don't bring back a message from me, he will take it out on that girl. And that you wouldn't like. Am I correct, machine?"

Mach grimaced, answer enough.

"So you will cooperate-and when Bane returns here, he will cooperate, because I have his girlfriend. We've got you, robot."

"Until Citizen Blue learns. Then you may not like the reckoning that comes."

"By the time Blue learns, there may have been a shift in the balance of power. Then I may like the reckoning well enough."

Mach realized that the cunning Citizen had big aspirations. He was going to use the contact with Phaze to increase his own power, making himself invulnerable to retribution. He could do that only with Mach's cooperation. Therefore the sensible thing to do was not to cooperate. But Fleta was indeed hostage, and until he knew she had been freed-and Bane knew Agape had been freed-they did indeed have to cooperate.

But his resources were not yet exhausted. He needed to distract the Citizen's attention from Agape for about twenty-four hours.

"I'll play you a Game," Mach said. "I will break out of this captivity within twenty-four hours. Then you may do with the alien female what you wish-but my father will settle with you for interfering with the Experimental Project and generating an interplanetary incident. I suspect he will simply ship you to Moeba for alien justice."

"I'll play no Game with you, robot!"

"You can't avoid it, Purple. You have already established it: you have taken me captive. My challenge is to break out. If I fail, I will have to cooperate with you. If I succeed, you will be finished. So it's your gain against your loss. But I'll offer you a draw at the outset: free me and the alien now, and there will be no retribution for what you have already done."

"You try to dictate terms to me, you inanimate contraption? I already hold the winning cards! There'll be no deal but this: you will deliver the message I send, or you will remain locked up forever!"

"So you decline the proffered draw," Mach said calmly. 'Then let the Game proceed. Twenty-four hours."

"There is no Game! No time limit!"