The woman shook her fringe of chestnut hair away from her eyes and peered again into the view-finder. “I’ll get to him as soon as I can, but it may be a while yet. I’d have had a plausible reason to contact him if he’d got into difficulties on the way up, and I can use the same reason if he has problems on the way down. Otherwise, I’m sure he’ll want to do the hard parts himself. If things go smoothly you shouldn’t expect us for another three days.”

“Three days!” The gruff voice was impatient. “Why so long? He’s at the top, isn’t he, that’s all he wanted?”

“He is.” The woman sounded amused. “And he’ll want to get down in his own way. If I try and contact him now, chances are he’ll tell me to get lost. That’s my opinion — check it with Caliban, if you don’t believe it.”

“I did.” The voice held grudging agreement. “We couldn’t make any sense of his outputs. I’ll ask Joseph to try him again, but I doubt if we’ll get anything new.”

While they were talking, Rob Merlin stood up, adjusted his face mask, and began to make his way to the final summit of K-2. When he reached it he remained there for only a couple of minutes, a tiny figure standing on top of the world. As he turned to begin the laborious descent his total attention was on the sloping ice walls and crevasses below him. They dipped and folded in dizzying complexity, all the way to his planned resting point four thousand feet further down. Full attention was crucial. At this height and pressure the blackened ice would sublime in the sunshine before it would melt — unless it had the force of his weight above it. With that weight, each footstep became perilous.

He never looked back up the mountain, or glanced towards the sun and the silver speck that was hidden in its bright glare. Ascent was the exciting part. Arrival at the summit never matched prior expectations; and descent, as always, would be the most dangerous.

At eighteen thousand feet there came a subtle but significant change in the surroundings.