(with Google + via rival site found via Google but not opened)

iii. is the first of this year's inevitable Buchan answers. It comes from Chapter One of 'Greenmantle'. Hannay receives a telegram from Sir Walter Bullivant of the F.O. and goes to see him...

Sir Walter shook hands with me and his eyes blinked a little.

'I may be sending you to your death, Hannay - Good God, what a damned task-mistress duty is! - If so, I shall be haunted with regrets, but you will never repent. Have no fear of that. You have chosen the roughest road, but it goes straight to the hill-tops.'

He handed me the half-sheet of note-paper. On it were written three words - 'Kasredin', 'cancer', and 'v. I.'

'That is the only clue we possess,' he said. 'I cannot construe it, but I can tell you the story...