Bob picked it up and placed it in his pocket. Although he was not aware of it at the time, it was the first piece of evidence in a mystery which was to pull him deep into its folds and require weeks of patient effort to untangle. The guard had edged over to the door and now reached out to pull it shut. Only a sharp order from Bob stopped him. “Keep your hands off the doorknob,” he ordered. “Someone was tampering here and I don’t want you messing your hands around the place.” The guard hesitated as though undecided whether to obey Bob, and the clerk stood up and doubled up a fist. “Better not touch that door.” There was a steelly quietness in the words that decided the guard, and he stepped well back into the corridor. “You’d better get back to your post. I’ll take care of this situation,” said Bob. “I’ll keep your flashlight and return it to you when I leave the building. I want to do a little scouting around and may need this light.” The guard grumbled something under his breath, but retreated down the corridor and finally vanished from sight. Bob disliked him thoroughly for his attitude had been one of sullen defiance; so unusual from the men generally on duty at night. It might be well to speak to Jacobs about it in the morning. Just to make sure that no one came along and touched the doorknob, Bob took out his handkerchief and tied it around the knob in a manner which would protect possible fingerprints. That done, he picked up the flashlight again and started to reconnoiter in the corridor, trying one door after another. There was just a possibility that the marauder had found a hiding place in an office which had been left unlocked. Bob knew that it was almost a useless quest, for the offices were checked each night. He made the rounds along one side of the corridor and started back on the side opposite his own office. The night lights were on and at the far end of the corridor it was necessary for him to use the flashlight. Door after door proved unyielding to his touch and he was about to give up the quest when he came upon a door that swung inward when his hands gripped the knob. Bob drew back suddenly and flashed the beam of light into the long room, which was almost identical with the one in which he had been working. What he saw there startled him more than he dared to admit later, and he stepped inside and moved toward the nearest desk. The ray from the flashlight revealed the utter confusion in the room. Baskets of papers on top of the desks had been upset and even the drawers in the filing cabinets had been pulled out and their contents hurled indiscriminately over the floor. A slight sound startled Bob and he swung around, the beam of light focusing on the door. It was closing—swiftly and silently. Bob leaped forward, stumbled over a wastepaper basket, and then reached the door which clicked shut just before he could grasp the handle.