That evening, after a hasty meal at home with Gwen, I went back to the garage, put on a greasy engineer's suit which I sometimes wore when doing dirty work around the cars, and buttoned over it a frayed tweed coat belonging to one of the men. Then, with a cap on and a pipe in my mouth, I went forth, and made my way on the top of a motor-'bus to the corner of Wimpole Street. If Flynn went out I intended to watch his proceedings, for though I entertained only a vague suspicion of Langton, yet I felt confident that his friend was not acting squarely. Have you ever been seized with misgivings of a person whom you have no just cause to doubt? Is not such a feeling the result of some unseen evil influence radiating from the person suspected--often quite rightly? My first impression of this specialist in diseases of the throat and nose was a bad one. Therefore, I strolled up the long, eminently respectable street, crossing Wigmore Street and Queen Anne Street, until a few doors on the left before coming into Great Marylebone Street, I halted before the house wherein the pair shared chambers. There were bright lights in their big sitting-room on the first floor, the room wherein Flynn had made those covert threats. It was then half-past eight. They would have dined by that hour, and if they were going out they would certainly very soon make an appearance. I strolled to the corner of Great Marylebone Street, and idled at the corner, watching. The evening was bright and cold, and many cabs were passing and repassing. I lit my pipe, and sauntered up and down, my eye ever upon the front door of the house wherein the two men lived. The time hung heavily, as it ever does when one is watching. An hour dragged by, but no one came out. At last, however, a maid ran up the area steps and came in my direction with a letter in her hand ready for posting in the pillar-box near which I was standing. As she stopped I spoke to her, but at first she hesitated to answer. After slipping five shillings into her hand, however, I induced her to tell me that the doctor had dined alone, and was sitting upstairs. Mr. Langton had, she said, left London early in the afternoon, but she was unaware of where he had gone. "Tell me," I asked the girl, "do they ever have a visitor named Kirk?" "Kirk!" she echoed. "Oh, yes, I recollect, 'e used to often call, but of late 'e 'asn't been." And she described my mysterious neighbour exactly. "When did he last call?" I asked. "Oh, I should say it 'ud be quite a month ago. 'E always used to arsk for the doctor." "Never for Mr. Langton?" "Not to my knowledge. Indeed, one afternoon when 'e called I told 'im that the doctor was out, but that Mr. Langton was at 'ome; but 'e told me that 'e wished to see the doctor an' nobody else." "How long has Doctor Flynn lived there?" I inquired. "About nine months." "Does he have many callers?" "No; they all go round to 'is consulting room in 'Arley Street, I believe."