asserts positively that the only person who entered the front door and passed down the main hall to this apartment was a man who rang the bell and, getting no answer, immediately walked out again. The other operator, who was on duty from ten o'clock until this morning, asserts with equal positiveness that no one entered the front door and passed the switchboard coming to this apartment. Add to all this the fact that every window on this floor is barred, and that no one from up-stairs can descend into the main hall without coming face to face with the operator, and we are, for the moment, confronted with an impasse."
Heath scratched his head, and laughed mirthlessly.
"It don't make sense, does it, sir?"
"What about the next apartment?" asked Vance, "the one with the door facing the rear passageway—No. 2, I think?"
Heath turned to him patronizingly. "I looked into that the first thing this morning. Apartment No. 2 is occupied by a single woman; and I woke her up at eight o'clock and searched the place. Nothing there. Anyway, you have to walk past the switchboard to reach her apartment the same as you do to reach this one; and nobody called on her or left her apartment last night. What's more, Jessup, who's a shrewd sound lad, told me this woman is a quiet, ladylike sort, and that she and Odell didn't even know each other."
"You're so thorough, Sergeant!" murmured Vance.
"Of course," put in Markham, "it would have
