At nine o'clock on the morning of the first of May, 1919, a young man spoke to the room clerk at the Bilt-more Hotel, asking if Mr. Philip Dean were registered there, and if so, could he be connected with Mr. Dean's rooms. The inquirer was dressed in a well-cut, shabby suit. He was small, slender, and darkly handsome; his eyes were framed above with unusually long eyelashes and below with the blue semicircle of ill health, this latter effect heightened by an unnatural glow which colored his face like a low, incessant fever.    Mr. Dean was staying there. The young man was directed to a telephone at the side. After a second his connection was made; a sleepy voice hello'd from somewhere above.