"You must watch for the system by which she communicates with her confederate in Richmond's house. They work the mails, but there must be some quicker means to use in emergencies.
"Try to snare a letter, or get a sight of the other party.
"And be sure not to jump at conclusions, Patsy. I've told you how the case looks, but it may be any other way. I haven't begun to work down to it yet."
Nick mounted his horse, and Patsy strolled away in the direction of the Stevens house.
When the detective got back to Colonel Richmond's, it was well along in the afternoon.
He spent the remainder of his day in exploring the secret recesses of the old house. It was, indeed, a marvelous place, and Nick got a very high opinion of the ingenuity of the man who had designed its mysterious passages.
He got little else, however. One or two discoveries he certainly made. They were important as indicating that somebody had recently been in the secret passages.
There was nothing to show what that person had been doing there, but the probability was, of course, that he had concealed himself in the old part of the house while preparing for his operations in Mrs. Pond's room, or while escaping from them.
These indications were very vague, and did not point to the principal in this affair—that mysterious thief who worked invisibly and by such strange methods.
After dinner Horace Richmond took Nick aside, for what he termed a discussion of "this ghostly rot."