de Marquet, fixing a strange look on my young friend.
"We'll see later how he got away from The Yellow Room," replied Rouletabille, "but he must have left the pavilion by the vestibule window."
"Once more,—how do you know that?"
"How? Oh, the thing is simple enough! As soon as he found he could not escape by the door of the pavilion his only way out was by the window in the vestibule, unless he could pass through a grated window. The window of The Yellow Room is secured by iron bars, because it looks out upon the open country; the two windows of the laboratory have to be protected in like manner for the same reason. As the murderer got away, I conceive that he found a window that was not barred,—that of the vestibule, which opens on to the park,—that is to say, into the interior of the estate. There's not much magic in all that."
"Yes," said Monsieur de Marquet, "but what you have not guessed is that this single window in the vestibule, though it has no iron bars, has solid iron blinds. Now these iron blinds have remained fastened by their iron latch; and yet we have proof that the murderer made his escape from the, pavilion by that window! Traces of blood on the inside wall and on the blinds as well as on the floor, and footmarks, of which I have taken the measurements, attest the fact that the murderer made his escape that way. But then, how did he do it, seeing that the blinds remained fastened on the inside? He passed through them like a shadow. But what is more bewildering than all is that it is
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