"Detson," he called out sharply, "I wish you would keep in sight. I have forgotten my instrument-case. Go to the office, tell my assistant to give it to you, and when you get it bring it to Room M." "Ay tank ay ban go queeck," said Nick, and away he hurried to the office. Soon, with the case in his hand, he went up the stairs, found the room, knocked at the door with an impatience which he had much difficulty in repressing. Doctor Holcomb opened the door, and the detective tried to peer into the room. To his disappointment, he was unable to see more than the foot of a bed, upon which some person was lying. The doctor received the instrument-case, uttered a curt "Thank you," and quickly closed the door. Nick would have remained by the door, but a moment after it closed Gabriel Leonard opened the door of a room opposite the head of the stairs and came toward him. His eyes were bloodshot, and there were marks of suffering on his face. The detective passed him half-way to the stairs, but Leonard did not look at the pseudo Detson. With his head bent, he walked quickly to Room M, and entered without knocking. Nick hastened down-stairs, saw Chick, and, seizing an opportunity when the corridor was clear, whispered a few rapid words. Chick nodded his head in comprehension, and, leaving the great detective, slouched along the corridor, mounted the stairs, and walked toward Room M. Once there, he sat down with his back against the door. He had been in that position about fifteen minutes, when conversation inside caused him to prick up his ears. He waited with every sense alert, and his heart beating at an unusual rate for ten minutes more; then, rising to his feet, flew, rather than ran, until he reached Nick. "Well," said the great detective quickly, his curiosity on edge. "You were right, then, Nick," said Chick, in a gasp. "The mystery will be solved in Room M. I have heard them talk. The last words of Leonard were: 'The hour has come. Now, good-by to St. Louis.'" CHAPTER VII. OUT OF DEATH'S SHADOW. Nick breathed heavily. The end was approaching. Chick's information told him that. "We've got Leonard in a box," said Chick. "We can drop on him right now, if you say so." "Now is not the time. We will wait until he comes out. Go up the stairs again, sit on the top step, and when Leonard enters his own room, let me know. If he does not go to his room, but comes down-stairs, follow him and inform me. I may be at the foot of the stairs when he leaves Room M. I shall try to be there. Now, go." The approach of an attendant caused Nick to cut short his talk and walk slowly away.