Two British travellers, Donald Kemp and Margaret Duncan, have disappeared in the wild mountainous region of northern Afghanistan; a terrain into which western Europeans seldom penetrate. The authorities in Kabul say that they have been murdered by the inhabitants of a small and primitive village and that retribution has already been exacted in the form of wholesale reprisals. John McLeod, a friend of the missing couple who has spent some years in Afghanistan as a diplomat, is deeply suspicious of these explanations.

He returns to Kabul and starts his own enquiries, but everywhere he is met with obstruction and evasion, though McLeod is deterred neither by the devious courtesies of local officials nor by the discreet negations of his own embassy. The quest becomes an obsession in which physical pursuit is linked with a personal desire to discover the truth of Donald and Margaret's whole strange relationship.