I never saw the grandmother, so I guessed she was bedridden. An old woman called Margit brought me my meals, and the innkeeper was around me at all hours. I wanted some time to myself, so I invented a job for him. He had a motor-bicycle, and I sent him off next morning for the daily paper, which usually arrived with the post in the late afternoon. I told him to keep his eyes skinned, and make note of any strange figures he saw, keeping a special sharp look-out for motors and aeroplanes. Then I sat down in real earnest to Scudder’s note-book.

He came back at midday with the Scotsman. There was nothing in it, except some further evidence of Paddock and the milkman, and a repetition of yesterday’s statement that the murderer had gone North. But there was a long article, reprinted from The Times, about Karolides and the state of affairs in the Balkans, though there was no mention of any visit to England. I got rid of the innkeeper for the afternoon, for I was getting very warm in my search for the cypher.

As I told you, it was a numerical cypher, and by an elaborate system of experiments I had pretty well discovered what were the nulls and stops. The trouble was the key word, and when I thought of the odd million words he might have used I felt pretty hopeless. But about three o’clock I had a sudden inspiration.

The name Julia Czechenyi flashed across my memory. Scudder had said it was the key to the Karolides business, and it occurred to me to try it on his cypher.

It worked. The five letters of ‘Julia’ gave me the position of the vowels. A was J, the tenth letter of the alphabet, and so represented by X in the cypher. E was XXI, and so on. ‘Czechenyi’ gave me the numerals for the principal consonants. I scribbled that scheme on a bit of paper and sat down to read Scudder’s pages.

In half an hour I was reading with a whitish face and fingers that drummed on the table.

I glanced out of the window and saw a big touring-car coming up the glen towards the inn. It drew up at the door, and there was the sound of people alighting. There seemed to be two of them, men in aquascutums and tweed caps.

Ten minutes later the innkeeper slipped into the room, his eyes bright with excitement.

‘There’s two chaps below looking for you,’ he whispered. ‘They’re in the dining-room having whiskies-and-sodas. They asked about you and said they had hoped to meet you here. Oh! and they described you jolly well, down to your boots and shirt. I told them you had been here last night and had gone off on a motor bicycle this morning, and one of the chaps swore like a navvy.’

I made him tell me what they looked like. One was a dark-eyed thin fellow with bushy eyebrows, the other was always smiling and lisped in his talk. Neither was any kind of foreigner; on this my young friend was positive.

I took a bit of paper and wrote these words in German as if they were part of a letter—

... ‘Black Stone. Scudder had got on to this, but he could not act for a fortnight. I doubt if I can do any good now, especially as Karolides is uncertain about his plans. But if Mr T. advises I will do the best I ...’

I manufactured it rather neatly, so that it looked like a loose page of a private letter.

‘Take this down and say it was found in my bedroom, and ask them to return it to me if they overtake me.’

Three minutes later I heard the car begin to move, and peeping from behind the curtain caught sight of the two figures.