Maybe Mother had found somebody's room to clean.

Graff stopped in for a brief visit on their first morning there, but then was off again-returned to Earth, in fact, on the shuttle that had brought them. He did not return for three weeks, by which time Peter had written nearly forty essays, all of which had been published in various places. Most of them were Locke's essays. And, as usual, most of the attention went to Demosthenes.

When Graff returned, he invited them to dine with him in the Minister's quarters, and they had a convivial dinner during which nothing important was discussed. Whenever the subject seemed to be turning to a matter of real moment, Graff would interrupt with the pouring of water or a joke of some kind-only rarely the funny kind.

This puzzled Peter, because surely Graff could count on his own quarters being secure. But apparently not, because after dinner he invited them on a walk, leading them quickly out of the regular corridors and into some of the service passages. They were lost almost at once, and when Graff finally opened a door and took them onto a wide ledge overlooking a ventilation shaft, they had lost all sense of direction except, of course, where "down" was.

The ventilation shaft led "down" ... a very long way.

"This is a place of some historical importance," said Graff. "Though few of us know it."

"Ah," said Father knowingly.

And because he had guessed it, Peter realized it should be guessable, and so he guessed. "Achilles was here," he said.

"This," said Graff, "is where Bean and his friends tricked Achilles. Achilles thought he was going to be able to kill Bean here, but instead Bean got him in chains, hanging in the shaft. He could have killed Achilles. His friends recommended it."

"Who were the friends?" asked Mother.

"He never told me, but that's not surprising-I never asked. I thought it would be wiser if there were never any kind of record, even inside my head, of which other children were there to witness Achilles's humiliation and helplessness."

"It wouldn't have mattered, if he had simply killed Achilles. There would have been no murders."

"But, you see," said Graff, "if Achilles had died, then I would have had to ask those names, and Bean could not have been allowed to remain in Battle School. We might have lost the war because of that, because Ender relied on Bean quite heavily."

"You let Ender stay after he killed a boy," said Peter.

"The boy died accidentally," said Graff, "as Ender defended himself."

"Defended himself because you left him alone," said Mother

"I've already faced trial on those charges, and I was acquitted."

"But you were asked to resign your commission," said Mother.

"But I was then given this much higher position as Minister of Colonization. Let's not quibble over the past. Bean got Achilles here, not to kill him, but to induce him to confess. He did confess, very convincingly, and because I heard him do it, I'm on his death list, too."

"Then why are you still alive?" asked Peter.

"Because, contrary to widespread belief, Achilles is not a genius and he makes mistakes. His reach is not infinite and his power can be blocked. He doesn't know everything. He doesn't have everything planned. I think half the time he's winging it, putting himself in the way of opportunity and seizing it when he sees it."

"If he's not a genius, then why does he Keep beating geniuses?" asked Peter.

"Because he does the unexpected," said Graff. "He doesn't actually do things remarkably well, he simply does things that no one thought he would do. He stays a jump ahead. And our finest minds were not even thinking about him when he brought off his most spectacular successes. They thought they were civilians again when he had them kidnapped. Bean wasn't trying to oppose Achilles's plans during the war, he was trying to find and rescue Petra. You see? I have Achilles's test scores. He's a champion suckup, and he's very smart or he wouldn't have got here. He knew how to ace a psych test, for instance, so that his violent tendencies remained hidden from us when we chose him to come in the last group we brought to Battle School. He's dangerous, in other words. But he's never had to face an opponent, not really. What the Formics faced, he's never had to face."

"So you're confident," said Peter.

"Not at all," said Graff. "But I'm hopeful."

"You brought us here just to show us this place?" said Father.

"Actually, no. I brought you here because I came up earlier in the day and swept it personally for eavesdropping devices. Plus, I installed a sound damper here, so that our voices are not carrying down the ventilation shaft."

"You think MinCol has been penetrated," said Peter

"I know it has," said Graff "Uphanad was doing his routine scan of the logs of outgoing messages, and he found an odd one that was sent within hours of your arrival here. The entire message consisted of the single word 'on'. Uphanad's routine scan, of course, is more thorough than most people's desperate search. He found this one simply by looking for anomalies in message length, language patterns, etc. To find codes, you see."

"And this was in code?" asked Father.

"Not a cipher, no. And impossible to decode for that reason. It could simply mean 'affirmative,' as in 'the mission is on.' It might be a foreign word-there are several dozen common languages in which 'on' has meaning by itself. It might be 'no' backward. You see the problem? What alerted Uphanad, besides its brevity, was the fact that it was sent within hours of your arrival-after your arrival-and both the sender and the receiver of the message were anonymous."

"How could the sender be anonymous from a secure militarydesigned facility?" asked Peter.

"Oh, it's quite simple, really," said Graff. "The sender used someone else's sign-on."

"Whose?"

"Uphanad was quite embarrassed when he showed me the printout of the message. Because as far as the computer was concerned, it was sent by Uphanad himself."

"Someone got the log-on of the head of security?" said Father.

"Humiliating, you may be sure," said Graff.

"You've fired him?" asked Mother

"That would not make us more secure, to lose the man who is our best defense against whatever operation that message triggered."

"So you think it is the English word 'on' and it means somebody is preparing to move against us."

"I think that's not unlikely. I think the message was sent in the clear. It's only undecipherable because we don't know what is 'on.'"

"And you've taken into account," said Mother, "the possibility that Uphanad actually sent this message himself, and is using the fact that he told you about it as cover for the fact that he's the perpetrator"

Graff looked at her a long time, blinked, and then smiled. "I was telling myself, 'suspect everybody,' but now I know what a truly suspicious person is."

Peter hadn't thought of it either But now it made perfect sense.

"Still, let's not leap to conclusions, either," said Graff. "The real sender of the message might have used Major Uphanad's sign-on precisely so that the chief of security would be our prime suspect."

"How long ago did he find this message?" asked Father

"A couple of days," said Graff. "I was already scheduled to come, so I stuck to my schedule."

"No warnings?"

"No," said Graff. "Any departure from routine would let the sender know his signal was discovered and perhaps interpreted. It would lead him to change his plans."

"So what do we do?" asked Peter.

"First," said Graff, "I apologize for thinking you'd be perfectly safe here. Apparently Achilles's reach-or perhaps China's-is longer than we thought."

"So do we go home?" asked Father