Upon the passage of the State prohibitory law every saloon in Riverbank had been closed and there had been growlings from the saloon element. Five of the leading prohibitionists had received threatening letters and, a few nights later, the houses of four of the five were blown up. Kegs of powder had been placed in the cellar windows of each of the four houses, wrecking them, and the fifth house was saved only because the fuse there was damp. Luckily no one was killed, but that was not the fault of the "dynamiters," as every one called them. The town and State immediately offered a reward of five thousand dollars for the arrest and conviction of the dynamiters, and detectives flocked to Riverbank. Real detectives came to try for the noble prize. Amateur detectives came in hordes. Citizens who were not detectives at all tried their hands at the work. For the first few days rumors of the immediate capture of the "ghouls" were flying everywhere, but day followed day and week followed week, and no one was incarcerated. The citizen-detectives went back to their ordinary occupations, the amateur detectives went home, the real detectives were called off on other and more promising jobs, and soon the field was left clear for Philo Gubb. Not that he made much progress. Each night he hid himself in the dark doorway of Willcox Hall waiting to pick up (Lesson Four, Rule Four) some suspicious-looking person, and having picked him up, he proceeded to trail and shadow him (Lesson Four, Rules Four to Seventeen). Six times--twice by Joe Henry--he was well beaten by those he followed. It became such a nuisance to be followed by Philo Gubb in false mustache or whiskers, that it was a public relief when Billy Getz and other young fellows took upon themselves the duty of being shadowed. With hats pulled over their eyes and coat-collars turned up, they would pass the dark doorway of Willcox Hall, let themselves be picked up, and then lead poor Detective Gubb across rubbish-encumbered vacant lots, over mud flats or among dark lumber piles, only to give him the slip with infinite ease when they tired of the game. But Philo Gubb was back the next night, waiting in the shadow of the doorway of Willcox Hall. He did not progress very rapidly toward the goal of the reward, but he counted it all good practice. But being beaten twice in succession by Joe Henry aroused his suspicion. Joe Henry ran a small carting business. He had three teams and three drays, and a small stable on Locust Street, on the alley corner. He was a great friend of Pie-Wagon Pete and he ate at the Pie-Wagon. Philo Gubb, after leaving Mr. Medderbrook, had not intentionally picked up Joe Henry. On his way to the Pie-Wagon it had been necessary for him to pass the alley opposite Joe Henry's stable and his detective instinct told him to hide himself behind a manure bin in the alley and watch the stable. In the warm June dusk he had crouched there, watching and waiting.