“I want to see the night clerk who was on duty last night, and——â€�

“He is here now, sir, in the office of the manager.�

“Very well. Show me to that office, and I will tell the manager of the other thing I want.�

“Right this way, Mr. Carter,� was the reply, and he was ushered to a hidden office behind the desk.

“I am Nick Carter,� he said abruptly, “with authority from headquarters. Mr. Brixton, you are the manager here?�

“Yes.�

“I want you to go with me now to the apartment occupied by one Henry Carroll; never mind why till we get there. I want this night clerk to accompany us.� And, on the way to the apartment mentioned, after he had overcome the objections of the manager, Nick asked the clerk:

“Who came into the building after the man Parsons made his appearance and went to the suite of Colonel Grafton?�

“Only Mr. Carroll. No one else.�

“Who went out of the building?�