“No; I don’t see how you could.  You did all that was possible under the circumstances.  You gave information, which is all that a private individual can do, especially if he is an overworked general practitioner.  But still, an actual crime is the affair of every good citizen.  I think we ought to take some action.”

“You think there really was a crime, then?”

“What else can one think?  What do you think about it yourself?”

“I don’t like to think about it at all.  The recollection of that corpse-like figure in that gloomy bedroom has haunted me ever since I left the house.  What do you suppose has happened?”

Thorndyke did not answer for a few seconds.  At length he said gravely: 

“I am afraid, Jervis, that the answer to that question can be given in one word.”

“Murder?” I asked with a slight shudder.

He nodded, and we were both silent for a while.

“The probability,” he resumed after a pause, “that Mr. Graves is alive at this moment seems to me infinitesimal.  There was evidently a conspiracy to murder him, and the deliberate, persistent manner in which that object was being pursued points to a very strong and definite motive.  Then the tactics adopted point to considerable forethought and judgment.  They are not the tactics of a fool or an ignoramus.  We may criticize the closed carriage as a tactical mistake, calculated to arouse suspicion, but we have to weigh it against its alternative.”

“What is that?”

“Well, consider the circumstances.  Suppose Weiss had called you in in the ordinary way.  You would still have detected the use of poison.  But now you could have located your man and made inquiries about him in the neighbourhood.  You would probably have given the police a hint and they would almost certainly have taken action, as they would have had the means of identifying the parties.  The result would have been fatal to Weiss.  The closed carriage invited suspicion, but it was a great safeguard.  Weiss’s method’s were not so unsound after all.  He is a cautious man, but cunning and very persistent.  And he could be bold on occasion.  The use of the blinded carriage was a decidedly audacious proceeding.  I should put him down as a gambler of a very discreet, courageous and resourceful type.”

“Which all leads to the probability that he has pursued his scheme and brought it to a successful issue.”

“I am afraid it does.  But—­have you got your notes of the compass-bearings?”

“The book is in my overcoat pocket with the board.  I will fetch them.”

I went into the office, where our coats hung, and brought back the notebook with the little board to which it was still attached by the rubber band.  Thorndyke took them from me, and, opening the book, ran his eye quickly down one page after another.  Suddenly he glanced at the clock.

“It is a little late to begin,” said he, “but these notes look rather alluring.  I am inclined to plot them out at once.  I fancy, from their appearance, that they will enable us to locate the house without much difficulty.  But don’t let me keep you up if you are tired.  I can work them out by myself.”