Inspector Burnley again made his way home. But it was not his lucky night. About half-past nine he was again sent for from the Yard. Some one wanted to speak to him urgently on the telephone. CHAPTER III THE WATCHER ON THE WALL At the same time that Inspector Burnley was interviewing Broughton and Harkness in his office, another series of events centring round the cask was in progress in a different part of London. Police Constable Z76, John Walker in private life, was a newly-joined member of the force. A young man of ideas and of promise, he took himself and his work seriously. He had ambitions, the chief of which was to become a detective officer, and he dreamed of the day when he would have climbed to the giddy eminence of an Inspector of the Yard. He had read Conan Doyle, Austin Freeman, and other masters of detective fiction, and their tales had stimulated his imagination. His efforts to emulate their heroes added to the interest of life and, if they did not do him very much good, at least did him no harm. About half-past six that evening, Constable Walker, attired in plain clothes, was strolling slowly along the Holloway Road. He had come off duty shortly before, had had his tea, and was now killing time until he could go to see the second instalment of that thrilling drama, ‘Lured by Love,’ at the Islington Picture House. Though on pleasure bent, as he walked he kept on practising observation and deduction. He had made a habit of noting the appearance of the people he saw and trying to deduce their histories and, if he did not succeed in this so well as Sherlock Holmes, he hoped he would some day. He looked at the people on the pathway beside him, but none of them seemed a good subject for study. But as his gaze swept over the vehicles in the roadway it fell on one which held his attention. Coming along the street to meet him was a four-wheeled dray drawn by a light brown horse. On the dray, upended, was a large cask. Two men sat in front. One, a thin-faced, wiry fellow was driving. The other a rather small-sized man, was leaning as if wearied out against the cask. This man had a black beard. Constable Walker’s heart beat fast. He had always made it a point to memorise thoroughly the descriptions of wanted men, and only that afternoon he had seen a wire from Headquarters containing the description of just such an equipage. It was wanted, and wanted badly. Had _he_ found it? Constable Walker’s excitement grew as he wondered.