Diamond nodded uncertainly.

“Now I suppose this would seem strange,” said Father. “If I knew as much as our scientists know, that is. I’ve been told that the magic baffles them and probably always will. Some deep thinkers actually claim that real demons inhabit the barrier, too many to count, and each demon spends its existence sending the heat down and the cold up while keeping the two atmospheres apart. But I’m a person who doesn’t need imaginary creatures. My mind is happy to accept the barrier as being just another beautiful mystery in a world full of nothing else.”

He paused, taking a deep breath.

“If you haven’t guessed, the coronas live in the lower half of the world. In their realm, the air is denser than water and fiercely hot. Take a ball—a hollow ball of our finest steel—and tie it to a steel cable. Then hover low and drop the ball through. Do you know what happens next?”

“It gets squashed,” Seldom said.

“And to retrieve the squashed ball, we have to drop ballast and use the fletch’s engines at full throttle,” Father said. “Which is another intriguing mystery: why is the barrier a lot more stubborn moving in one direction over another?”

The valley was finished, except it didn’t end where Diamond expected. The ground simply dropped into a lower valley that hung over the open air. They were still standing in shadow, the sun hiding behind the reef’s edge. But the day was far enough along that Diamond could stare down at what looked like yellow mist, smooth and bright. He didn’t blink, and his eyes didn’t ache. Glancing up at his father, he discovered that the man was gazing up, not down.

“Dawn is the brightest time,” Father said. “That’s because when day begins, very little grows between us and the sun. But that transparency doesn’t last. Minutes after the rain rises, new plants begin growing. The coronas’ realm is full of spores and seeds, and little creatures that swim in that dense air, and before your first meal sits happy in your stomach, a new forest is thriving below us. By midday, the forest is thick enough that the sun is noticeably weaker. By dusk, that air is choked with bladder plants and new generations of odd birds, and the coronas are feasting. The sun vanishes for us, but it never weakens, and for that matter, it never grows brighter. Night comes to us because all of the sunlight is trapped by that hot young forest. Likewise, just before dawn is the blackest moment, and sometimes it feels as if the world will never feel day again.”

The running man finally caught up to them, breathing hard and quick to apologize for being late. “Baby-Tam gave me a message. We can’t call Ivory Station now.”

Father nodded. “The line is broken.”

The man was carrying dark tubes tipped with glass disks. Handing them to Father, he said, “Yeah, and how did you know?”

“I’m a pessimist. And thanks for bringing these.”

Father handed one tube to Diamond, and then he walked a few steps back with the other man, giving fresh commands.

Diamond turned the tube between his hands.

“Do you know what that is?” asked Seldom.

“You do,” he guessed.

“Oh, it’s just a telescope,” Elata said. And she pulled at one end, the tube becoming four linked tubes. “Look through the little end.”

Diamond put an eye to the glass and stared at the valley below.

Father returned and opened the second telescope, but he looked up and out with his bare eyes. “I don’t quite trust these toys,” he said. “They narrow your vision down to one tiny, spellbinding spot.”

Diamond lowered his telescope.

“Can I?” asked Seldom.

He handed it over.

“Night,” said Father again. “It happens here, and in a different fashion, it happens below us. The corona forest keeps growing where it can, but only close to the sun. The farther places, like underneath the reef, fall into their own darkness. And remember. One night can seem long to us, but for those hot fast-living plants, darkness is death. They spread seeds and spores as they die, and the animals lay eggs, and the forest closest to the sun thrives to the end, but the end finds some way to happen. Ends always do. Vapor that was part of the morning air is now tied into the new wood and meat. The dense hot air makes fire inevitable. Sparks happen. You’re never sure where the blaze starts, but it spreads quickly, and the day-old forest explodes. Except this is nothing like our little fires. There are no ashes. No smoke. This is an explosion, an explosion so vast that even the stubborn demons stop doing their work. Steam and thunder rise through the floor, and by the time the steam reaches our old slow trees, it has cooled to where it doesn’t cook us, and slow cold life can grow a little more.”

Father paused, staring at the same point for a long moment. Then he put the telescope to his eye, focusing by turning the littlest tube. What he saw brought silence and then a soft sigh, and then he lowered the telescope, closing it back into one tube.

Seldom aimed in the same direction.

“What do you see?” Elata asked.

“Nothing,” he said. Then he laughed nervously and said, “No, there’s a big airship. Near the canopy, pointed this way.”

The two men glanced at each other. Father handed the telescope to the Master as he began talking again.

“The forest explodes,” he said. “Seeds and spores and the tough eggs can withstand the steam. The only living creatures that survive are the coronas. At least nothing that I’ve seen, and I’ve watched that realm longer than anyone else alive, I’d guess.

“I know coronas. And by ‘know,’ I mean I’m a little better than most when it comes to guessing where they’ll be tomorrow and which one is the easiest to stalk and how to make my kill without killing myself. Which is why an old man can do a young man’s job.”

He gave his son another smile and wink. “I’m sure your mother has mentioned how much I enjoy being a slayer.”

“You hate it,” Diamond said.

“The killing and carving up of these big magnificent beasts, each one older than me and sometimes ancient. But there is one blessing that found me only because I spent my life going out into the sky and killing giants.”

He took his son under his arm and said nothing.

“What?” Diamond asked.

“I want you to know why,” Father said. “Why your mother and I feel so fortunate to know you, whatever you are.”

Lowering the telescope, the Master made a sorry sound.

“What?” Elata asked. “What did you see?”

Nissim shook his head and touched Father on the shoulder, the two men exchanging slow significant nods.

With one finger, Father touched Diamond on his tiny, tiny nose. “The coronas like to visit our world. And do you know why?”

The boy shook his head.

“I don’t know why either. But I know how they do it. Each one of these creatures is full of bladders. It inhales the hot dense air and compresses the air even more than before, and when the bladders open, a roaring jet comes out of their central mouths. That’s what throws it past the stubborn demons. And then the corona’s black muscle inflate the same bladders, making them round and swollen but with nothing inside. Nothingness is lighter than hydrogen. The vacuum buoys the creature up into what has to feel frigid and dry.”

“They come to feed,” Seldom said.

“Sometimes,” Father said. “I’ve seen them hunting for meat at the bottom of the canopy, which means they’re hungry, maybe. But they’re more likely to ignore easy meals. If they were humans, I’d describe them as being curious wanderers, but they aren’t human and ‘curious’ might mean nothing to them. Usually they travel alone, and I don’t know why. My sense is that they’re not loners by nature. In fact, I’d wager quite a lot that they’re intensely, obsessively social creatures. Even alone, they are constantly, constantly talking to one another. One of their voices is deep and loud, bladder spitting out words that shake our world. And they also leak stinks that make other coronas happy or angry, and they have special organs hidden under every scale. They’ll lift those scales and produce brilliant light. The color of that light can change instantly. Color has meaning. Certain patterns are exceptionally important, and I’ve deciphered a few words and concepts, but really I know nothing. Nothing. And nobody else understands the coronas. But I’ll tell you what most of the slayers believe; the real reason they rise into the high thin empty air is the same reason why people stand on a stage when they have important opinions to share: from high, they can broadcast their brilliance down to their entire world.”