"About what?"

Ray shrugged his shoulders in blank ignorance. Then he said, "We have advanced one step toward the solution of the problem, my dear Jack. But we have not gone very far."

He took the copy of the cryptogram from my writing-table and again examined it. The figures "6.11" puzzled him. Many times he referred to them.

Four days passed, during which we kept strict observation upon Karff and followed him wherever he went. On the fifth day, Ray having spent all the morning watching him, to relieve him I walked along the Theobalds Road a few minutes before one and paused, as usual, before the oil shop at the corner. There was no sign of my friend, and though I waited through the whole of that cold afternoon and evening, continuing my wearisome vigil till midnight, yet he did not come.

Much surprised, I returned to New Stone Buildings, where I found a telegram from Ray, sent from Waterloo Station at three o'clock, telling me that all was right, and urging me to await further information.

This I did. For a whole week I possessed myself in patience, not knowing where Ray was or what had befallen him. That he was on the trail of a solution of the mystery was evident, but he sent me no word of his whereabouts.

It was apparent, however, that he was no longer in London.

Eleven days after his disappearance I one afternoon received another telegram, which had been handed in at Chichester, asking me to go at once to the Queen's Hotel at Southsea, where he would meet me at ten o'clock that night.

At the hour appointed I awaited him in my bedroom overlooking Southsea Common and the harbour, and at last he joined me. I saw by the serious expression upon his face that something unusual had happened.

"The fellow Karff has realised that I'm following him, Jack. Therefore you must take the matter up. He's in the service of a greengrocer in Queen Street, close to the Hard. I haven't yet discovered his game."