"Or what?" he mocked. "You'll kill me? You'll kill me anyway."

I was panting. My mind was racing madly. What game was this man playing?

How could I win? "Why would I kill you?"

"I'm a Yeerk," he said. "A Controller. Although my host and I are on very good terms. I made him rich. I wrote his famous Web browser. We've been partners all these years."

"Yeerks don't have partners," I said.

He laughed. "No," he drawled, "we don't." He looked at me with a sharp, shrewd look. "Who sent you after me? Have you made some kind of deal with my brother?"

"Your brother?"

"You are obviously Andalites," he said patiently. "No one else has your amazing morphing technology. But I have to ask myself, why would Andalites go to so much trouble to kill me? Me, of all Yeerks?"

I was totally confused. I hesitated.

"This is weird," Marco said, sending me a private thought-speak message.

"This guy is cornered," Cassie said. "He thinks he's toast. You can see it in his eyes. We need to find out more."

I paced a little. Tigers get restless just standing. Should I take a chance? Should I tell him at least some of the truth?

"We traced you here from the Web page. The one about Yeerks." He nodded. "Yes, but why come after. . . ?" His face lit up. "Of course!

You were looking for allies! You weren't sure, were you? You thought perhaps it was all real, that humans were forming a resistance to the Yeerk invasion of their planet! You came here to see if I was for you, or against you!"

Then he began to laugh. He laughed in that sick way people do when they're laughing but nothing is funny.

"Shall I tell you who and what I am, Andalite? Shall I?"

I didn't answer. I waited.

"My Yeerk designation is Esplin-Nine-Four-Double-Six. Note the 'double six.' Do you know what it means?"

"No."

"A 'double' designation means that I am a twin. That two Yeerks grew from the same grub.

When there are twins, one is considered the prime, and one the lesser. I am the lesser. My brother, my twin, is the prime. To him go the best assignments, the best hosts, the rank, the power, the glory.

And to me, only what I can take." He made a fist on the word "take." "In some cases, brothers can share. In some cases, twins can even become allies. But not with my brother. My brother is power mad. Or maybe just mad now. He left me nothing. He assigned me to a poor, unimportant human host. This Joe Bob Fenestre, a lowly programmer working in the bowels of a telephone company.

"Well, that wasn't good enough. I wanted more. And if I couldn't have it as a Yeerk, I'd have it as a human. I ended up making an alliance with my host. We were two of a kind. Two losers in the shadow of our betters.

I used Yeerk technical knowledge to make Fenestre rich. And in the process, I created Web Access America, which made me the greatest source of information on humans there was. I knew secrets my brother could only guess at."

"You sift E-mail. You spy on chat rooms." "You know human computer terminology," he said.

I swallowed hard. I'd been careless. I had sounded "human." Bluff it out. "We Andalites are a small, hunted band on this planet. Knowledge is survivals

He seemed satisfied with that.

"I became an invaluable asset to the invasion. All by myself I had become a powerful human with vast information. But of course, my brother couldn't tolerate that. He had me declared a traitor. He cut me off from the Kan-drona. He would have killed me. For the crime of being as great as he, he'd have murdered me."

Joe Bob Fenestre's eyes bored into me. And I felt a chill of premonition. See, right then I knew who this twin brother was. Who he had to be.

"0h, my God," Cassie whispered. She'd guessed, too.

"Yes, only one twin can be great," Fenestre said bitterly. "Only one of us could be the mighty Visser Three."

first encountered Visser Three within minutes of finding the Andalite prince, Elfangor.

Visser Three showed up and murdered the helpless Elfangor. Since that time we have fought him many times. He is the only Yeerk in all the universe ever to have successfully taken over an Andalite body, long ago in another war on another planet. When he took the Andalite body as a host, he acquired the Andalite's ability to morph. He is the only morph-capable Yeerk.

And now I understood why his brother, this Yeerk living in the head of Joe Bob Fenestre, would instruct his men to shoot at birds and any other animal they saw. Any one of them might be Visser Three in morph.

"I gather, from your silence, that you know my brother," Fenestre said.

"We have fought him," I said simply.

"And yet, you're still alive. Not many can say that. My compliments."

"How do you survive without having access to the Yeerk pool? I see you have created a replica here in this room, but surely you haven't managed to create your own Kandrona to supply the vital Kandrona rays." Fenestre nodded. "Well, well. So you know a Yeerk pool when you see one.

And you know about the Kandrona." He shrugged. "I have found a way to stay alive without a Kandrona. That's not important. What's important is ... what now?"

"He's lying," Cassie whispered instantly. "0r at least he's not telling the whole truth. The Kandrona. He doesn't want to talk about that." I nodded my tiger head. It probably looked funny, such a human gesture coming from the huge cat. "Your brother must know where you are. He could kill you anytime he wants. He could hit you from orbit and leave this place a big, smoky ruin."

"No, no, that would be too noisy. Some idiot human with a camcorder could manage to record it."

"He could send in Hork-Bajir. They'd cut

through your guards just like we did. Or he could come himself. If he wanted to kill you, he would. He could. He hasn't. So why not?" Fenestre smiled a wintry smile. "Clever, clever Andalites. So good with your computers and your magnificent Dome ships. You still think you're the lords of the galaxy, don't you? We spread from planet to planet and you keep falling back. And yet your arrogance is so unbelievable you never pause to consider that maybe you're not so clever, after all."