Travis as a suspect, that I made it my first duty this morning to examine this door and the mysterious little passageway back of it.  When first notified of this door, we had been assured that it had not been opened in years, that the only key remaining to it was the one the Curator showed us hanging from the ring he drew from his own pocket; and acting upon these statements, which I would not allow myself to doubt for a moment, we decided to open the door in our own way, which we immediately did.  The result was the instant discovery that some one had passed through this door and down these stairs very much later than years ago.  We could see, without taking a step beyond the doorway, traces of a well-shod foot in the dust lying thickly on every tread.  These traces were so many and so confused that I left them for Stevens’ experienced eye and deft manipulation to separate and make plain to us.  He is making an examination of them now, and will be able to report to you before night.”

The Inspector was a man of little pretense.  He felt startled and showed it.

“But this is a serious matter, Gryce.”

“Very serious.”

“No mere visitor to the museum would have presumed upon this venture.”

“No.”

“Which means——­”

“That some one actively connected with it had a guilty hand in this deplorable affair.”

“I am afraid so.”

“Some one well acquainted with the existence of this door and who had means of opening it.  The question is—­who?”

In saying this, Mr. Gryce studiously avoided the Inspector’s eye; while the Inspector in his turn looked up, then down—­anywhere but in the detective’s direction.  It was a moment of mutual embarrassment, broken, when it was broken, by a remark which manifestly avoided the issue.

“Possibly those traces you speak of were not made at the time you specify.  They may have been made since, or they may have been made before.  Perhaps the Curator was curious and tried his hand at a little detective work on his own account.”

“He hadn’t the chance.  Every portion of the building has been very thoroughly guarded since first we entered it.  He may have gone up prior to the shooting.  That is open to dispute; but if he had done so, why did he not inform us of the fact when he showed us the key?  The Curator is the soul of honor.  He would hardly deceive us in so important a matter.”

The quick glance which this elicited from the Inspector awoke no corresponding flash in the eye of the imperturbable detective.  He continued to shake his head over the small object he was twirling thoughtfully about between his thumb and finger, and only from his general seriousness could the Inspector gather that his mind was no more at rest than his fingers.  Was this why his remark took the form of a question?

“Where was the Curator when you forced open that door behind the tapestry?  Was he anywhere in the building?”