Geena struggled out of her seat, and pulled closed the hatch in the roof. Soon after, Henry heard a muffled thud, as the techs shut the outer hatch.

And so he was sealed up in the ultimate enclosure: a cell within which he couldn’t even stand up, and yet which would carry him away from the Earth.

He searched for some reflection of this in Geena’s eyes. But there was none; Geena’s expression was cloudy, distracted. After a couple of seconds she turned back to her checklist, and worked through instrument settings, exchanging messages with the crisp Russian voices of the ground control in their bunker.

Jane understood the problem. In the last couple of weeks she’d heard about other planes which had run into this difficulty. But knowing didn’t help; she knew, in fact, that the outlook for their survival wasn’t good.

The volcanic debris, silicate ash suspended in the air, fused when it came into contact with the hot metal of an aeroplane’s combustion chambers and turbines. It was like damping a fire with sand. Engines just flamed out.

Through the windows she could see how the hot grit had sandblasted the 747’s leading edges. The paint was stripped, the windscreen and landing light covers opaqued. The dust got into the aircraft’s pitot tubes — airspeed sensors — and caused conflicting information on the flight deck. The engine nacelles, intakes and fans looked as if they had been shot-blasted.

The crew allowed Jane onto the deck — Jack was here, wide-eyed — but they barely reacted to her presence.

The cabin was filled with a bluish, acrid mist, sucked in by the compressors before the engines died. There was only grey cloud ahead of the aircraft, dancing electric light on the windscreen.

The Crew were following their procedures, the drill Jane recognized as preparing for an in-flight start-up of the engines.

They all looked incredibly young.

“…Mayday, mayday, mayday. Our position is forty miles west of Glasgow. We have lost all four engines. We’re descending and we’re out of level 370.”

Prestwick here, have you got a problem?

“We’ve lost all four engines.”

Understand you have lost engine number four?

The Senior First Officer — a thin, nervous young man — groaned at his captain, a competent fifty-ish woman. “The fuckwit doesn’t understand.”

Jack’s eyes got rounder.

“Then tell her until she bloody does,” the captain said. “Tell her we want radar assistance to get back to Prestwick. What about number four?”

“Fully shut down.”

“All right.” The captain checked the position of that engine’s fire handle and thrust lever. “We’ll go for a restart. Begin the checklist.”

The crew struggled through their checklists and drills — start levers to cut-off, standby ignition on, start levers back to idle — and Jane felt for them, forcing themselves through their complex procedures, mastering their own fear.

Kerosene ignited in the engine, and a huge flame shot from the jet efflux. But the engine didn’t restart.

The silence was eerie. Jane could hear the crew’s scratchy breathing.

The captain was using her autopilot, Jane saw. Five hundred feet per minute descent. She picked up a little of what was happening from the crew’s terse conversation. They were trading height for speed; their airspeed was two hundred and seventy knots, somewhere near the speed for minimum drag for the present all-up weight. And the pilot was turning back towards Prestwick. Good, Jane thought, somebody who knows what she is doing. Even after total engine failure, the aircraft was still under control. In fact it could glide for another twenty minutes or more from this height, and surely the engines would restart at a lower altitude.

But still, a dead stick unpowered landing back at Prestwick — or worse, a ditching — would be no fun.

A warning horn sounded in the cockpit. Cabin pressure was dropping. No air was being pumped into the aircraft.

Oxygen masks dropped before the crew, and they fitted them to their faces. There was none for Jane and Jack, where they stood at the back of the cabin. The flight engineer’s mask didn’t fall properly; he had to get out of his seat and pull it down, but when he did so the supply hose just fell to pieces.

“Shoot,” the captain said softly. She disconnected the autopilot, dropped the aircraft’s nose and pulled on the speed brake lever. There was a rumble, and Jane braced herself. The captain was throwing away her precious height, the height which could be traded for speed and distance, which might save all of their lives. But now she had no choice.

The altimeter dropped steadily. But Jane could see that the electrical garbage in the atmosphere outside was playing hell with the instruments. The inertial navigation systems showed random digits and patterns, and the distance measuring equipment was blank altogether. Even communication with Prestwick was disrupted by bursts of static.

The SFO said, “We might have water contamination in the fuel tanks. And in that case—”

“There’s no way the engines will start again. Oh, shoot.” The captain looked ahead steadily. “All right. We’ll head towards Prestwick, and then turn westbound to ditch. You know the drill. Land along the line of the primary or predominant swell, and upwind into the secondary swell, or downwind into the secondary swell…”

“My God,” Jane whispered.

She felt a stab of anger. To have come so close, to have survived so much. And now, even as they were escaping from the blighted country, this.

The wounded plane flew on as the crew worked steadily.

“Five minutes,” Geena told Henry. “Close your helmet.”

Henry pulled down his visor. His breathing was loud.

Geena reported, “We are in the preparation regime. Everything on board is correct. And everything is correct in the control bunker.”

A reply, in Russian and English.

“Shit hot,” Henry said quietly.

“Two minutes,” Geena said evenly.

He looked across at her. “This is one hell of a strange divorce we’re having, Geena,” he said.

She ignored him.

Still there was no countdown.

And a little after that—

There was a rumbling, deep below, beneath his back. It was like an explosion in some remote furnace room.

An analogue clock started ticking on the control panel. It was the mission clock.

Oh Christ, oh Christ. They were serious, after all. They really had fired this thing, with Henry and his ex-wife stuffed in the nose. And now—

“One minute before the turn,” the SFO said.

The aircraft had been without engines for twelve, thirteen minutes, Jane estimated. She had lost count of the number of restart attempts while she’d been up here, and there surely wouldn’t be time to restart now. There were maybe five minutes left before the ditching.

Jane listened to the crew’s diagnosis and projection. With only battery power, there would be no radio altimeter for precise height indication. Not even any landing lights. The captain wouldn’t be able to lower her flaps, so the ditching would be fast — faster than the stall speed of a hundred and seventy knots — the engines would surely break off on impact; the wings and structure would be damaged…

The cloud cleared; low sunlight poked into the cabin, briefly dazzling Jane. The play of electrical light over the windscreen dissipated.

The flight engineer cried out. “Number four has restarted!”

Now Jane felt the roar of the engine; she could see the engine gauges rising, the power settling. Gingerly the captain advanced the thrust lever, and the engine was running at normal power.

They had ducked under the ash cloud, she realized; that was what had enabled the engines to start.

“Here comes number two,” the captain said.