“I took the bottle to her the next day. The moment it was in her hands she said to me, ‘I must have more than this, madam. I must have the letters you have found. They are your justification for planning your husband’s death, and I must have them to show in my defence if I get into trouble for assisting you.’ “I had been weak enough to tell her nearly everything I have told you, because I couldn’t bear to let her think that I was a bad woman acting from evil motives. Now I repented too late. As usual, she had a perfect answer to everything I could say. ‘It comes to this, madam, that you have given me the means to commit a murder, and you have made these letters your excuse. If you decline to produce them I must doubt if they exist, and as an honest woman I shall hand this bottle over to the police.’” Tarleton got out of his chair. If he did not yet know all he wanted to know, he knew all that this poor woman could tell him. “Thank you. If I have your permission to use this information in my own way neither you nor your daughter need fear anything more.” The astonished woman stopped him on the way to the door. “But after Madame Bonnell had got the letters she turned round and refused to go on with the plot. How did my husband die?” “I am going to ask her that.” CHAPTER XX THE FINGER-PRINT When Sir Frank Tarleton walked into the room on his return from Paris the first thing he did was to put his gold repeater to his ear and make it ring out its musical notes. It was the sign of triumph. He told me everything just as I have described it. Then he transfixed me with a question. “I expect you to be as candid with me as Mrs. Neobard has been. Did you put this poison into Wethered’s cup along with the opium?” It was no more than I ought to have expected; no more than I had deserved. But it gave me a greater shock than I could have thought possible. “Before God I am innocent of that!” I swore. My chief received my oath without any indication of belief or disbelief. “I don’t blame you for anything else you did on behalf of Lady Violet,” he said gravely. “Even if you hadn’t been in love with her, as a man you could do no less than you did to save her from such a scoundrel. You were right to drug him and right to destroy his case-book. But you had no right to take his life.” I looked him in the face. I was too proud to repeat my denial. “That has been my greatest anxiety in the whole business, Cassilis. I liked you; you knew it, and I think you should have confided in me.” “It wasn’t my secret,” I pleaded. “I suppose that was the reason: yes, I accept that. It was a mistake, though, because you had no chance of keeping the secret. That is partly why I think it better for you to drop this kind of work and go in for private practice. You lack the first essential for a detective, my dear fellow; you can hold your tongue, but you can’t hold your face.” I’m afraid I couldn’t hold it then. It blushed in spite of me.