Presently the lad, whistling blithely, hurried along. At a discreet distance Entwistle followed, noting with satisfaction that the boy lingered outside a cinema palace. "He would have spent that half-dollar had the place been open," he theorised. "As it is, he'll go home to his dinner and he won't say a word about the wrong change." Keeping within sight of his chase, Entwistle followed until the boy turned down a narrow street close to Bootham Bar--one of the still-existent gateways of mediaeval York. On the other hand the roadway was bounded by the masonry of the city wall. Entwistle followed no further. He promptly ascended the steps of Bootham Bar and gained the paved walk that runs along the top of the walls. From his coign of vantage he watched, and saw the lad enter a house--stopping, however, to glance up and down the cobbled street. "Good enough for the present," soliloquised Entwistle. "I feel fairly satisfied with my morning's work. Until to-night there's nothing doing, so I will have a little relaxation from duty. Philip, my festive, you can be reckless: you can have a whole coupon's worth of roast beef at the best restaurant in York." Having done ample justice to the inner man, Entwistle decided to put in an hour or two at the railway station. Railway stations had a peculiar fascination for him. Incidentally he had obtained a good many clues while waiting on a platform, although he was bound to admit that the almost general use of motor cars had robbed the railway of a questionable record of affording quick transit to fugitive criminals. As he entered the booking hall he ran against a familiar figure wearing an unfamiliar garb--a thick-set, clean-shaven man of about forty-seven or eight, in height about five feet ten. He was in R.A.F. officer's uniform. Just beneath his cap his iron-grey closely-cropped hair contrasted forcibly with his brown, almost reddish complexion. "B a r c r o f t !" exclaimed Entwistle. "What on earth are you doing here? And in uniform, too. By Jove! I'm pleased to see you." "I'm here for fifteen and a half minutes more," replied Peter Barcroft, consulting his wristlet watch. "That is, if the North Eastern Company run their train punctually. That's question one answered. I'm in uniform because I wanted to be, and didn't mean to be out of the fun. What are you doing, might I ask?" "Same old thing--'the trivial round, the common task' sort of business, you know," answered the Secret Service man. "But you've not explained: how comes it that you are in khaki?" "I suppose," replied Barcroft, "it's a case of 'following in father's footsteps' reversed. I'm a mere 'second loot'; my son Billy is now a major, so if I meet him in public I must salute him. This war's been responsible for a lot of funny incidents and conditions, hasn't it?"