The old man sat with his mouth open, staring wildly at Holmes.  Amazement and fear were stamped upon his expressive features.  Now, with an effort, he shrugged his shoulders and burst into insincere laughter.

“All very fine, Mr. Holmes,” said he.  “But there is one little flaw in your splendid theory.  I was myself in my room, and I never left it during the day.”

“I am aware of that, Professor Coram.”

“And you mean to say that I could lie upon that bed and not be aware that a woman had entered my room?”

“I never said so.  You were aware of it.  You spoke with her.  You recognized her.  You aided her to escape.”

Again the professor burst into high-keyed laughter.  He had risen to his feet, and his eyes glowed like embers.

“You are mad!” he cried.  “You are talking insanely.  I helped her to escape?  Where is she now?”

“She is there,” said Holmes, and he pointed to a high bookcase in the corner of the room.

I saw the old man throw up his arms, a terrible convulsion passed over his grim face, and he fell back in his chair.  At the same instant the bookcase at which Holmes pointed swung round upon a hinge, and a woman rushed out into the room.  “You are right!” she cried, in a strange foreign voice.  “You are right!  I am here.”

She was brown with the dust and draped with the cobwebs which had come from the walls of her hiding-place.  Her face, too, was streaked with grime, and at the best she could never have been handsome, for she had the exact physical characteristics which Holmes had divined, with, in addition, a long and obstinate chin.  What with her natural blindness, and what with the change from dark to light, she stood as one dazed, blinking about her to see where and who we were.  And yet, in spite of all these disadvantages, there was a certain nobility in the woman’s bearing—­a gallantry in the defiant chin and in the upraised head, which compelled something of respect and admiration.

Stanley Hopkins had laid his hand upon her arm and claimed her as his prisoner, but she waved him aside gently, and yet with an over-mastering dignity which compelled obedience.  The old man lay back in his chair with a twitching face, and stared at her with brooding eyes.

“Yes, sir, I am your prisoner,” she said.  “From where I stood I could hear everything, and I know that you have learned the truth.  I confess it all.  It was I who killed the young man.  But you are right—­you who say it was an accident.  I did not even know that it was a knife which I held in my hand, for in my despair I snatched anything from the table and struck at him to make him let me go.  It is the truth that I tell.”

“Madam,” said Holmes, “I am sure that it is the truth.  I fear that you are far from well.”

She had turned a dreadful colour, the more ghastly under the dark dust-streaks upon her face.  She seated herself on the side of the bed; then she resumed.