“Why, no, not exactly,” she replied, after a brief scrutiny. “I really don’t believe that it is his. But I did not notice it, Mr. Carter, at the time. I felt a bit nervous and hastened upstairs to find him.” Nick remembered having observed it, and he now had positively fixed the identity of the woman seen on the stairs. He took the note from her again and asked: “Was this brought to you by one of the servants?” “No, it was not.” “By whom?” “It was slipped into my hand by a man clad in a Mexican costume. I was surprised, of course, but I opened and read it. The man then had disappeared. I wondered how he had identified me, of course, but I supposed that Archie had told him what costume I was wearing. That made me nervous, you see, for I feared he might be ill. I could think of no other reason for his wanting me.” “When had you previously seen him?” “Not for half an hour, Mr. Carter, or longer.” Nick took the note from her again, saying, while he slipped it into his pocket: “I will keep this for a time, Mrs. Waldmere, if you have no objection.” “None whatever.” “Tell me, now, what costume your husband wore.” “That of a Spanish cavalier.” “Did he have it made, or rent from a costumer?” “He hired it from Perrot, in Fifth Avenue.” “And yours?” “Came from the same place. Some of the jewels have been added, and will be removed before I return it,” said Mollie, pointing to some of the ornaments. Nick gazed thoughtfully at the floor for a moment, then turned to Mr. Carrington. “Your guests were admitted by card, I believe?” he said inquiringly. “Yes. Each presented an invitation card to Perkins, the butler, with the bearer’s name and that of the costume worn.” “Who now has the cards?” “Perkins has charge of them.” “Have him bring them here,” Nick directed. “I wish to examine them.” Mr. Carrington withdrew to find the butler. “When did you decide to wear this costume, Mrs. Waldmere?” Nick then asked, turning to her again. “Oh, nearly a week ago,” said Mollie. “I engaged it of Perrot about that time.” “Who except him knew you were to wear it? Did you inform any person?” “Only one, aside from my husband and the servants, who may have heard me discussing it with him,” said Mollie. “I told one intimate friend of mine, Clara Ringold, of Brooklyn. She and her husband were invited and intended coming, but I have not seen either of them. Something must have prevented them.” “What costume was she to wear?” “That of a cabaret singer. She has a beautiful voice. We confided in one another, Mr. Carter, that we might recognize each other during the evening.” “Where were you at that time?” “When we confided in one another?” “Yes.” “I was calling on Mrs. Ringold in her Brooklyn residence. That was several days ago.” “Were you alone with her?” “Yes. We were seated in the library.” “She is the wife of the Honorable Charles Ringold, I take it, who was a member of the last Congress.” “Yes, the same,” bowed Mrs. Waldmere. “She----”