My companion gave a sudden chuckle of comprehension. “And not a very obscure cipher, Watson,” said he. “Why, of course, it is Italian! The A means that it is addressed to a woman. ‘Beware! Beware! Beware!’ How's that, Watson?

“I believe you have hit it.”

“Not a doubt of it. It is a very urgent message, thrice repeated to make it more so. But beware of what? Wait a bit, he is coming to the window once more.”

Again we saw the dim silhouette of a crouching man and the whisk of the small flame across the window as the signals were renewed. They came more rapidly than before—so rapid that it was hard to follow them.

“PERICOLO—pericolo—eh, what's that, Watson? ‘Danger,’ isn't it? Yes, by Jove, it's a danger signal. There he goes again! PERI. Halloa, what on earth—”

The light had suddenly gone out, the glimmering square of window had disappeared, and the third floor formed a dark band round the lofty building, with its tiers of shining casements. That last warning cry had been suddenly cut short. How, and by whom? The same thought occurred on the instant to us both. Holmes sprang up from where he crouched by the window.

“This is serious, Watson,” he cried. “There is some devilry going forward! Why should such a message stop in such a way? I should put Scotland Yard in touch with this business—and yet, it is too pressing for us to leave.”