"She wore yellow," Mason said, like it was important. With his left hand, he twiddled with a glass of whiskey. "That was why we saw her."

He stared silently into his glass for a moment. The only sound was the buzz of a distant lawnmower.

I coughed. "I'm really here about the map."

"First I have to tell you about her," he snapped, eyes blazing. "Do you know Everest? Isn't what it used to be. And I'm not talking about the earthquake. Hundreds climb it every year. Like a bloody motorway to the summit." He grunted. "But I was offered the impossible. A secret route no one had ever used."

"By who?"

"A Sherpa, called Da-Nu."

"And he had the map."

"Yes. He had your map." Mason swirled his glass. "We did it, but it was difficult. Then on the way back down I saw her, just a smudge of colour against all that white and black. She had severe altitude sickness. Her own party had left her to die."

"Why?" I asked, shocked.

"Oxygen," he said simply. "You carry only enough for yourself. The added exertion of carrying someone else will kill you." He swigged whiskey. "Kill all of you."

"What happened?"

"We had to leave her to die," Mason said irritably. "Couldn't even stay with her until the end. She begged me to, but I couldn't." He swallowed. "You have to believe that."

I nodded. "So this Da-Nu has the map?

"He vanished afterwards, but when I got back to England that woman stayed with me. I never knew her name, but her eyes… her voice. I would hear her sometimes, at night. So I had to go back. To bring her down." He refilled his glass without offering me any.

"Did you find Da-Nu?"

"No. A Lama near Gorakshep gave me the map, but he said it would bring only balance. Buddhist nonsense. On the way up the weather was filthy, but when it lifted I saw everything was wrong." Mason shook his head. "And then I heard a voice."

"The woman?" I asked, hardly believing.

"Of course not," Mason snapped. "It was a climber, with a broken leg. His party had abandoned him. But we had enough oxygen to get him down safely."

"And the map?"

"Lost," Mason said vaguely. "I lost it digging him out." He whistled out a sigh. "So if you want the map I had, it's gone."

I glanced down at the table to hide my irritation, then nodded. "Well, thank you for your time."

"If I were you, I'd forget it," Mason muttered. "It isn't what you think it is." He raised his right hand and pointed at me.

It was a blackened, dead-looking stump. The stub of a finger and thumb clung to it like barnacles on a rock.

"Frostbite," Mason said. "Digging him out. We might have saved him, but I still hear her voice, every night. Where is the balance in that?"

He turned away, and I left him to his whiskey and his memories.