Hardly a day of his life passed without Mr. Llewellyn John having cause to be thankful for the inspiration that had resulted in the founding of Department Z. Nothing seemed to come amiss, either to the Department or its officials. They never required an elaborate filling-up of forms, they never asked for further particulars as did other departments. They just got to work. Mr. Llewellyn John had, once and for all, defined Department Z. when he said to Mr. Thaw, "If I were to ask Scotland Yard if Chappeldale had gone over to the Bolshevists, or if Waytensee had become an Orangeman, they would send a man here, his pockets bulging with note-books. Department Z. would tell me all I wanted to know in a few hours." In his first interview with Mr. Llewellyn John, previous to being appointed to Department Z., Malcolm Sage had bluntly criticised the Government's methods of dealing with the spy peril. "You're all wrong, sir," he had said. "If you spot a spy, you arrest, imprison or deport him, according to the degree of his guilt. Any fool could do that," he had added quietly. "And what would you do, Sage?" inquired Mr. Llewellyn John, who never took offence at the expression of any man's honest opinion, no matter how emphatically worded. "I should watch him," was the laconic reply. "Just as was done before the war. You didn't arrest spies then, you just let them think they were safe." For a few moments Mr. Llewellyn John had pondered the remark, and then asked for an explanation. "If you arrest, shoot or intern a spy, another generally springs up in his place, and you have to start afresh to find him; he may do a lot of mischief before that comes about." Sage gazed meditatively at his finger-nails, a habit of his. "On the other hand," he continued, "if you know your man, you can watch him and generally find out what he's after. Better a known than an unknown danger," he had added oracularly. "I'm afraid they wouldn't endorse that doctrine at Scotland Yard," smiled Mr. Llewellyn John. "Scotland Yard is a place of promoted policemen," replied Sage, "regulation intellects in regulation boots." Mr. Llewellyn John smiled. He always appreciated a phrase. "Then you would not arrest a burglar, but watch him," he said, glancing keenly at Sage. "The cases are entirely different, sir," was the reply; "a burglar invariably works on his own, a spy is more frequently than not a cog of a machine and must be replaced. He seldom works entirely alone." "Go on," Mr. Llewellyn John had said, seeing that Sage paused and was intently regarding his finger-nails of his right hand. "Even when burglars work in gangs, there is no superior organisation to replace destroyed units," continued Sage. "With international secret service it is different; its casualties are made good as promptly as with a field army." "I believe you're right," said Mr. Llewellyn John. "If you can convince Colonel Walton, then Department Z. can be run on those lines."