“Never mind how I know,” replied Nick, sternly. “It is my business to know a great many things. But I want to say this: I mean to investigate this matter to the bottom. If you help me by giving me all the information in your possession, so much the better, but whether you do or not I shall find all out. Now choose which you will do.” “Well, I had intended to retain you, but this letter——” “Let me see it,” demanded Nick, in a decided tone. Mr. Cary yielded, and, taking the letter from his breast pocket, handed it to Nick. At a glance the famous detective saw that it was the same handwriting, on the same kind of paper, as the two letters he had received in the morning. It read: “Dear Papa Cary: I want to warn you against a very bad man. His name is Nick Carter. You will only get yourself into trouble if you don’t take my warning. You are in a good deal of trouble now, for you stand in danger of exposure. Fie! Such a naughty Papa Cary! But you must not talk to Nick Carter. You must not talk to him of our pleasant experiences last night. And, Papa Cary, you must come again, and bring some more of the stuff that makes the mare go. I shall tell you when and where. And you must, or there will be pretty photographs sent to Mamma Cary and the little Carys, and to the bank officials, and so there will if you talk to Nick Carter. “The Brown Robin.” Nick folded up the letter and placed it in his pocket, saying: “This letter will be safer with you than with me. Now tell me how you met the woman.” “How do you know——” “I would rather you would answer my question,” interrupted Nick, sternly, “and please waste no time with questions. You met a woman last night. Where? How? When?” “Well, it was in the Rideau restaurant—that is a——” “I know—in Fourth Avenue. How came you to be there?” “Some business took me on the East Side yesterday afternoon, on which I was delayed beyond my own dinner hour. I had heard of this place and thought I would like to visit it. So I went there to dine. It was crowded, few seats being vacant. “As I passed down the rows of tables I came to one at which was seated a young woman of attractive appearance, dressed like a lady, in brown, on whose hat was a robin. “The seat opposite her was vacant, and, bowing, I asked if I could occupy it. She consented by saying that she could not prevent me, as it was free to any one to take. “Seating myself, it was not long before I was in conversation with her.” “I see,” said Nick. “Did she know who you were?” “Why, no.” “Then how did she come to know?” “That is where I was a fool. I told her.” “On her inquiry?” “No, confound it. A bottle of wine and a pretty woman let loose my tongue, and I babbled like an infant.” Nick had difficulty in keeping a straight face over this frank confession and the disgusted face that accompanied it. “Of course you didn’t know her?” asked Nick.