The door of the left-hand flat upon the third landing was standing ajar. Gregson pushed it open. Within all was absolute silence and darkness. I struck a match and lit the detective’s lantern. As I did so, and as the flicker steadied into a flame, we all gave a gasp of surprise. On the deal boards of the carpetless floor there was outlined a fresh track of blood. The red steps pointed towards us and led away from an inner room, the door of which was closed. Gregson flung it open and held his light full blaze in front of him, while we all peered eagerly over his shoulders.

In the middle of the floor of the empty room was huddled the figure of an enormous man, his clean-shaven, swarthy face grotesquely horrible in its contortion and his head encircled by a ghastly crimson halo of blood, lying in a broad wet circle upon the white woodwork. His knees were drawn up, his hands thrown out in agony, and from the centre of his broad, brown, upturned throat there projected the white haft of a knife driven blade-deep into his body. Giant as he was, the man must have gone down like a pole-axed ox before that terrific blow. Beside his right hand a most formidable horn-handled, two-edged dagger lay upon the floor, and near it a black kid glove.

“By George! it’s Black Gorgiano himself!” cried the American detective. “Someone has got ahead of us this time.”

“Here is the candle in the window, Mr. Holmes,” said Gregson. “Why, whatever are you doing?”

Holmes had stepped across, had lit the candle, and was passing it backward and forward across the window-panes. Then he peered into the darkness, blew the candle out, and threw it on the floor.

“I rather think that will be helpful,” said he. He came over and stood in deep thought while the two professionals were examining the body. “You say that three people came out from the flat while you were waiting downstairs,” said he at last. “Did you observe them closely?”

“Yes, I did.”

“Was there a fellow about thirty, black-bearded, dark, of middle size?”

“Yes; he was the last to pass me.”

“That is your man, I fancy. I can give you his description, and we have a very excellent outline of his footmark. That should be enough for you.”

“Not much, Mr. Holmes, among the millions of London.”

“Perhaps not. That is why I thought it best to summon this lady to your aid.”

We all turned round at the words. There, framed in the doorway, was a tall and beautiful woman - the mysterious lodger of Bloomsbury. Slowly she advanced, her face pale and drawn with a frightful apprehension, her eyes fixed and staring, her terrified gaze riveted upon the dark figure on the floor.

“You have killed him!” she muttered. “Oh, Dio mio, you have killed him!” Then I heard a sudden sharp intake of her breath, and she sprang into the air with a cry of joy. Round and round the room she danced, her hands clapping, her dark eyes gleaming with delighted wonder, and a thousand pretty Italian exclamations pouring from her lips. It was terrible and amazing to see such a woman so convulsed with joy at such a sight. Suddenly she stopped and gazed at us all with a questioning stare.

“But you! You are police, are you not? You have killed Giuseppe Gorgiano. Is it not so?”

“We are police, madam.”

She looked round into the shadows of the room.

“But where, then, is Gennaro?” she asked. “He is my husband, Gennaro Lucca. I am Emilia Lucca, and we are both from New York. Where is Gennaro? He called me this moment from this window, and I ran with all my speed.”

“It was I who called,” said Holmes.

“You! How could you call?”