"For instance?" he suggested encouragingly.
"If I left this office locked when I went out to lunch, for instance, and found it still locked but the papers slightly disarranged on my return," she replied.
"Anything more?"
"It is very unpleasant to set traps, of course, but if I put a little dab of typewriter ink on the inner handle of the door when I next went out, and subsequently found a slight stain of a similar colour on my white glove after shaking hands with some one, the suspicion would be deepened."
"I think that the matter is of sufficient importance for you to tell me all you know," he said gravely. "If you hesitate to be definite for fear of making a mistake, I will take pains to verify your suspicions and I will accept all responsibility."
"Then I accuse Mr Tantroy of being a paid spy in the service of the Government."
"Tantroy!" exclaimed Salt with a momentary feeling of incredulity. "Tantroy! It seems impossible, but, after all, it is possible enough. You know, of course, that he has a room here now, and might even think in his inexperience that he was at liberty to come into this office at any time."
"But not to take impressions of my keys and have duplicates made; nor to copy extracts in my absence; nor to open and examine the cipher typewriter."
"Has that been left unlocked?" he demanded sharply.
"No," she replied. "You have the only key that I know of. But it has been unlocked, and I infer that the code has been copied."