As this, however, was apparently not in dispute, it furnished no new information. Thorndyke’s object⁠—for I felt certain that he had something definite in his mind⁠—must be to test something apart from the genuineness of the signatures. But what could that something be? I dared not ask him, for questions of that kind were anathema, so there was nothing for it but to lie low and see what he would do with the photographs.

The whole series was finished on the fourth morning after my adventure at Sloane Square, and the pack of cards was duly delivered by Polton when he brought in the breakfast tray. Thorndyke took up the pack somewhat with the air of a whist player, and, as he ran through them, I noticed that the number had increased from twenty-three to twenty-four.