“It’s only in the past months that we’ve become aware of it. But once we cast back to look for his tracks, the last sure sighting we could come up with was in August of ’21.”

“Where was that?”

“In the hills above Simla. He stopped the night with an old acquaintance, and told her that he was going back to Tibet for a time, although he intended a detour to Lahore first to visit a friend.”

“But the friend in Lahore never saw him?”

“We could uncover no one in Lahore who had seen him. In fact, we couldn’t even find anyone there who would admit to being O’Hara’s friend.”

“And the amulet?”

“Ah. That arrived ten weeks ago. By post.” The dry answer forestalled any exclamations, for clearly the surprise of such an unadorned delivery had sent waves through the department, leaving a thousand questions in its wake. Holmes ventured one of those.

“Posted where?”

“In Delhi. Handed in at an hotel by a French tourist, a lady here to paint botanical watercolours. She was given it by a middle-aged Parsi who guided her through the gardens in Bombay, requesting that favour in return.”

“Extraordinary. I don’t suppose you still have the paper it came wrapped in?”

“Of course. It’s in my safe, if you’d like to see it.”

“Very much.”

I broke in with a question. “Pardon me if I ask things I either should not, or which I ought to know already, but was Mr O’Hara still on what you might call ‘active duty’?”

“Not really. After the War, with the Bolsheviks apparently having their hands full in Russia, we had all begun to think we might relax our guard and turn to other concerns. Since O’Hara’s expertise is that of the borders and Tibet, he sat at a desk for a year, possibly a bit more, then in late 1920 asked for a holiday. He was forty-five and had not taken one since returning from Tibet when he was nineteen, so one could scarcely object. But when we needed him this past autumn and went looking, we couldn’t find him.”

“You say you needed him. The Russians are back?” Holmes asked.

“If not yet, then soon. You know that Labour will grant the Bolsheviks formal recognition?”

“It is to be expected.”