“Heavy vegetation there in the valley. And along the foot of the Great Escarpment. Resinated trees and shrubs, for the most part. Also fireseed trees— you know. Species that require fire to propagate. Engineered at Biotique. Thorny resin manzanita, blackthorn, giant sequoia, some others.”

“How do you know this?”

“I planted them.”

“And now you’ve set them on fire?”

Sax nodded. He glanced down at the smoke.

“But Sax, isn’t the percentage of oxygen in the atmosphere really high now?”

“Forty percent.”

She stared at him some more, suddenly suspicious. “You jacked that up too, didn’t you! Jesus, Sax— you might have set the whole world on fire!”

She stared down at the bottom of the column of smoke. There in the big trough of Kasei Vallis was a line of flame, the leading edge of the fire, burning brilliant white rather than yellow— it looked like molten magnesium. “Nothing will put that out!” she cried. “You’ve set the world on fire!”

“The ice,” Sax said. “There’s nothing downwind but the ice covering Chryse. It should only burn a few thousand square kilometers.”

Nadia stared at him, amazed and appalled. Sax was still glancing down at the fire, but most of the time he watched the plane’s instruments, his face set in a curious expression: reptilian, stony— utterly inhuman.

The metanat security compounds in the curve of Kasei Vallis came over the horizon. The tents were all burning furiously, like torches of pitch, the craters on the inner bank like beach firepits, spurting white flame into the air. Clearly there was a strong wind pouring down Echus Chasma and funneling through Kasei Vallis, fanning the flames. A firestorm. And Sax stared down at it unblinking, his jaw muscles bunched under the skin.

“Fly north,” Nadia ordered him. “Get clear of that.”

He banked the plane, and she shook her head. Thousands of square kilometers, burned— all that vegetation, so painstakingly introduced— global oxygen levels raised by a significant percentage. . . . She regarded the strange creature sitting beside her warily.

“Why didn’t you tell me about this?”

“I didn’t want you to stop it.”

As simple as that.

“So I have that power?” she said.

“Yes.”

“Meaning I’m kept ignorant of things?”

“Only of this,” Sax said. His jaw muscles were bunching and relaxing, in a rhythm that reminded her suddenly of Frank Chalmers. “The prisoners were all moved out into asteroid mining. This was the training site for all their secret police. The ones who would never give up. The tortures.” He turned that lizard gaze on her. “We’re better off without them.” And he returned to his piloting.

• • •