On the floor, Gerald Whitmore shifted, his expensive leather shoes kicking against the pedestal of the observer’s seat.

“We’re going to suffocate,” Whitmore whimpered, clutching his silk tie to his mouth. “He’s killed us. He’s killed us all.”

“Shut up, Gerald,” I said, not looking at him.

My focus was on the digital timer in Thorne’s hand.

The red numbers flickered. 01:12.

“What is that device, Aris?” I asked, stepping toward him.

“A simple regulator,” Thorne said, adjusting his spectacles with his free hand. “It controls the solenoid valves in the air conditioning packs. Once it reaches zero, the auxiliary flow stops completely.”

“You’re going to poison three hundred people?” I asked.

“Not poison, Grace,” he said, looking down at his polished shoes. “Just sleep. A quiet, permanent sleep.”

“Grace,” Malachi called out, his voice small. “The nose is dipping. The horizon line on the screen is tilting.”

I lunged back to the co-pilot’s seat, leaning over the pedestal to look at the primary flight display.

The artificial horizon was leaning five degrees to the left, and the altitude digits were beginning to tick downward.