“I see. That office was supposed to be deserted all the afternoon?”
“Correct.”
“Yet some one was concealed in there, and heard and saw all that was said and done in Redway’s office?”
“I believe so. Whoever it was, he or she made a mistake.”
“By forgetting to remove the mirror?”
“Exactly. And unless I am much mistaken that mirror will trap the person we want.”
“How?”
“If it disappears from its place high up there on the wall before to-morrow—and I think it will.”
“I see, I see. You have arranged to find out who goes into that office?”
“Yes. The janitor will keep me posted.”