Diamond thought of Sophia and Tar`ro.

Bits must have thought the same. He turned, looking at the open doorway. But the person was a teacher, and she ran past their door, racing for her own classroom.

Diamond watched the back of the teacher’s head, and then he glanced down, discovering the gun that filled Bits’ right hand.

Drop-suits lay in heaps. Two older students made it their job to sort the suits according to size. There were always more suits than people. Nobody would be left behind. The blimp was tiny, barely enough room available for this class, but if the worst happened and Marduk fell, other children and teachers could slide into these suits and leap, throwing open their arms and legs while gliding away from the trunk.

Various adults had explained that emergency plan with brash confidence. But his parents didn’t share their faith, and neither did Nissim. The Master admitted that falling trees loved to spin and often tumbled end over end. Lucky people existed. Some avoided every hazard and broke only bones when they finally struck the canopy dangling from the neighboring tree. A few landed on an airship floating nearby, or on rare occasions, they grabbed a dangling net or rope. There were even cases where people fell past the canopy, and then ignoring the long odds, they were plucked from the air before dropping into the superheated realm where the corona ruled.

Diamond had made that long fall, saved by his father. But he didn’t need his father because the blimp was outside the window. Four black-clad police officers had turned into six, and they were making another attempt to shove the obstinate walkway into the window, aiming for nobody but Diamond.

Master Nissim was still sitting.

Diamond stood beside his guard, which was what he was supposed to do. But they kept backing away from the open window, which wasn’t expected.

Good had a special name for the police.

“Go go go turd-men!” he shouted.

Elata spun around. She wanted to say something to Diamond, and it surprised her to see him standing in front of the animal cages.

She put a hand beside her open mouth.

Then a single shout began. People across the school were screaming. So many voices poured from every classroom that the emergency bells and the blimp horn seemed to grow quieter.

Elata turned back to the window, looking outside.

The Master was holding a tiny knife in his hand. The large green chrysalis was in the middle of desk, pulled open at the seam, gray fluids slowly seeping across clean paper and old books, and the Master didn’t notice the mess, looking at Bits and at Diamond and then back at Bits.

Every other student in the class was standing beside the open window, staring into the distance. Seldom’s face was twisted, eyes crying and the mouth shouting, “No it can’t be no no . . . !”

Diamond followed those eyes.

The next nearest tree was Rail. Rail was half-again larger than Marduk and exceptionally strong.

But Rail seemed to be moving.

How could that be?

For no fathomable reason, that great ancient tree was plunging towards the floor of the world.

Two dozen guards had been chosen to protect Diamond. Brave talk said that the special unit was pulled from a thousand eligible candidates, but Nissim never believed in large, easily rounded numbers. There were only so many retired soldiers with the training, the clearances, enough youth, and open-minded attitudes. What’s more, every guard had to be local, loyal to the Corona District and to its Archon, with a family history that didn’t cross its pollen with the wrong kinds of humans.

Papio, in other words.

There were probably less than a hundred potential bodies to fill out questionnaires and endure the tedious interviews and endless background checks, and a surprising portion of them had made it through the gauntlet.

But knowing your own soul was impossible enough. What about people dedicated to protect a half-human child? That’s why the duty rosters were intentionally complicated and sometimes blatantly random. Each shift varied in length, and schedules could be replaced without warning, and individual guards couldn’t be certain that they would work tomorrow. Since trust wasn’t tested until there was an attack, no guard was ever permanently teamed up with colleagues. Sometimes an armed man sat inside Nissim’s classroom and then outside the boy’s home, and then he wasn’t seen again. Twenty days later, Nissim mentioned the missing guard. He tried to sound glancingly curious, as if the matter was barely worth the breath. Of course nobody explained anything to him. But a person could learn a lot from the way stern faces wouldn’t quite look at him, dismissively telling the empty air, “You’re just the teacher. This is a personnel matter. Don’t ask.”

In those early, learn-as-you-go days, guards came to school in pairs. Two guns seemed like plenty with the police floating outside and nothing but children and rule-hungry adults inside. But the job was evolving. Rumors of threats and rumors of spies kept finding their way to Nissim. The papio had spies everywhere and ten different plans to steal the boy. And the District of the Districts wanted him in their giant hands too. And meanwhile, a hundred little tribes of scared people were talking about abominations and what must be done to save this sorry wicked world.

One day someone inside the Archon’s office decided that three guards was the superior number, which puzzled the Master until he gave it a little thought.

Picking his moment and his target, he said, “I want to ask a question.”

“I won’t talk about the job,” said the guard, flat out.

“I wouldn’t dream of trying,” Nissim said.

Tar`ro was sitting near classroom’s front door. The other guards were at their stations, beside the window and in the back. The students and one monkey were standing and kneeling in front of the biggest cage. A young fire spider was being fed, except Nissim had already fed it, in secret. A terrified scurry-champ was running away from its fears, but the hairy blue spider showed little interest in this uncooperative second meal.

“You wouldn’t dream, huh?”

They were sitting close, talking quietly. Tar`ro had a narrow mouth and chin but bulging cheek bones, making it appear as if two dissimilar faces had been glued together. A master at the art of looking everywhere and seeing just enough, Tar`ro was usually the first guard to notice when something new was brought into the classroom or when an artifact had been taken away. And sometimes he showed lesser talents, like traces of sarcasm, and even better, a tiny capacity for doubt.

“Tell me your question,” he said.

Nissim asked, “How many legs does it take to build a stool?”

Tar`ro saw the point immediately. “You want me to say, ‘Two isn’t good enough.’ Is that right?”

“But two is enough. It requires balance, but balance is possible.”

“Until you quit paying attention, and then you fall over.” Tar`ro liked the game enough to grin. “Three legs make the stool stable. That’s what you want me to say.”

“Except four legs work even better.”

The guard shrugged. “Which means more wood and more precision, what with getting each piece to be the same length. Look at your old desk, standing crooked on the floor.”

“I like my desk,” the teacher said.

“Good for you,” said the guard. “But talking about stools, let’s say that maybe we’re already at the bottom of our inventory when it comes to working legs. Ever think in those terms?”

“Never,” Nissim said.

The grin came again, and Tar`ro looked at him, hard. “I know all about you.”

“I’m sure you do.”

“You’re the professor who got fired. Then you were the butcher who got old inside the freezer. But now you lucked into this easy job because that boy likes you and his folks want you here. Merit and Haddi demanded you, in fact. And you happen to be a damn smart man who makes every other teacher in this place feel like an idiot.”