She had been around the front of the house for some little time, and then, as if satisfied that Mr. Mountain was housed for the night, had left, going directly to the corner of Thirty-fourth Street and Sixth Avenue, where she met two men, evidently awaiting her coming. Only a word or two was exchanged between them, and they then set off at a quick pace, going straight to the Thirtieth Street house, where the Brown Robin had unlocked the doors and let the two men in. She did not enter the house herself, but now hurried to Lexington Avenue, where she took the car, getting off at Twenty-third Street, and going to the Seventeenth Street house, which she entered some time after midnight. She was there but a short time, when she came out clad in woman’s clothes, and went straight to the Lexington Avenue house, evidently her day’s work done. “Well,” said Nick, “it was a hard day’s work, and she filled in all her time. “She was arranging her programme for to-morrow. We have arranged our programme, too. Those two men that she let into the Thirtieth Street house are there to help her in the strike on Mr. Mountain. “I doubt if there will be any others on hand. You need not watch it this morning. My plans have been slightly changed since my talk with Mr. Mountain last night. “But I want you to put yourself in a place outside where you can follow me this morning when I go out: I suppose the Brown Robin will try to spring her trap on me this morning.” Patsy had been gone but a few moments when a messenger boy arrived with a letter for Nick. It was signed by Mrs. Ansel, and said that the place appointed for her in which to meet the Brown Robin was in Seventeenth Street at eleven o’clock, and it asked if Mr. Carter would meet the writer at a well-known department store in Sixth Avenue at 10 A. M., naming the entrance at which Mrs. Ansel would be waiting. Nick carefully examined the letter and noted several things. The stationery was not the same as that which had been used for the former letters; the handwriting was not the same, and the letter was framed so skillfully that it was made to look like the letter of a woman asking an assignation with a man. Nick called Edith and asked her to read the letter. As Edith was doing so he took some papers from his pocket, and from these selected a blank sheet and an envelope. “Compare this blank paper and the paper on which this note is written,” said Nick. “It is the same,” said Edith. “Even the most cunning make their slips,” said Nick. “I found this blank paper on a table in the parlor of the Brown Robin in Lexington Avenue, as I did also a sheet of the other paper. Keep them, and the letter as well. “I am off to meet this very cunning person and see what her little game is. I confess I can’t quite see through it.” He went away, and promptly at ten appeared at the entrance of the department store named.