Walking close along the wall, to avoid the creaking floor boards, Philo Gubb, paper-hanger and student of the Rising Sun Detective Agency's Correspondence School of Detecting, tiptoed to the door of the bedroom he shared with the mysterious Mr. Critz. In appearance Mr. Gubb was tall and gaunt, reminding one of a modern Don Quixote or a human flamingo; by nature Mr. Gubb was the gentlest and most simple-minded of men. Now, bending his long, angular body almost double, he placed his eye to a crack in the door panel and stared into the room.