The registered letter from Tim Fisher culminated this six years of frantic search. Unlike the previous leads, this spoke with authority, named names, gave dates, and outlined sketchily but adequately the operations of the young man in very plausible prose. Then the letter went on in the manner of a man with his foot in a cleft stick; the writer did not approve of James Holden's operations since they involved his wife and newly-adopted daughter, but since wife and daughter were fond of James Holden, the writer could not make any overt move to rid his household of the interfering young man. Paul Brennan was asked to move with caution and in utter secrecy, even to sending the reward in cash to a special post-office box. Paul Brennan's reaction was a disappointment to himself. He neither felt great relief nor the desire to exult. He found himself assaying his own calmness and wondering why he lacked emotion over this culmination of so many years of futile effort. He re-read the letter carefully to see if there were something hidden in the words that his subconscious had caught, but he found nothing that gave him any reason to believe that this letter was a false lead. It rang true; Brennan could understand Tim Fisher's stated reaction and the man's desire to collect. Brennan even suspected that Fisher might use the reward money for his own private purpose. It was not until he read the letter for the third time that he saw the suggestion to move with caution and secrecy not as its stated request to protect the writer, but as an excellent advice for his own guidance. And then Paul Brennan realized that for six years he had been concentrating upon the single problem of having James Holden returned to his custody, and in that concentration he had lost sight of the more important problem of achieving his true purpose of gaining control of the Holden Educator. The letter had not been the end of a long quest, but just the signal to start. Paul Brennan of course did not give a fig for the Holden Estate nor the welfare of James. His only interest was in the machine, and the secret of that machine was locked in the young man's mind and would stay that way unless James could be coerced into revealing it. The secret indubitably existed as hardware in the machine rebuilt in the house on Martin's Hill, but Brennan guessed that any sight of him would cause James to repeat his job of destruction. Brennan also envisioned a self-destructive device that would addle the heart of the machine at the touch of a button, perhaps booby-traps fitted like burglar alarms that would ruin the machine at the first touch of an untrained hand. Brennan's mind began to work. He must plan his moves carefully to acquire the machine by stealth. He toyed with the idea of murder and rejected it as too dangerous to chance a repeat, especially in view of the existence of the rebuilt machine.