"Yes, the house next to the one you entered on that fatal night was in the occupation of Madame," she explained. "We seldom went there, however, although I personally preferred the bright life in Kensington to that at Hampton. From the many private conversations, meaning looks and mysterious whisperings exchanged between Madame and Mrs. Blain there was soon aroused within me a vague suspicion that something secret was in progress. I liked old Mr. Blain exceedingly, and Mary became my best friend; nevertheless, my misgivings were strengthened, when one day Hartmann, unusually shabbily dressed and accompanied by the Blains, arrived at The Hollies and the trio were closeted for quite an hour with Madame. At length there also arrived a youngish good-looking man with a lady of about his own age, and they were at once admitted to the drawing-room, being enthusiastically welcomed. After half an hour or so we all dined together, but in the drawing-room before dinner I noticed two tumblers half-filled with dirty water, in one a tiny glass rod evidently used for mixing, as though Hartmann had been exhibiting some of his secret experiments. On entering the dining-room, Madame introduced her new guests to me as Mr. and Mrs. Coulter-Kerr, and sitting beside the husband I found him a most interesting and intelligent man, who literally adored his wife. In the course of conversation it transpired that the newly-arrived pair were from India, and had taken the Blains' town house for the season, and further, that Hartmann, who had apparently become one of their most intimate friends, had established his laboratory in one of the top rooms of that house." She paused and glanced across to the detective, who was listening attentively with folded arms. As she related her story her great clear eyes became more luminous.