“We—no, sir, not right away. We stopped for a few moments there in the lobby to talk about the type of poker we wanted to play. Miss Payson had lost money on one of these wild poker games where the dealer has the opportunity of calling any kind of game he wants, some of them having the one-eyed Jacks wild, and things of that sort.”

“How long were you talking?”

“Oh, a couple of minutes.”

“And then went right up?”

“Yes.”

“Where was the elevator?”

“The elevator was on one of the upper floors. I remember we pressed the button and it took a little while to come down to where we were.”

“That’s all,” Mason said.

Della Street’s fingers dug into his arm. “Aren’t you going to ask him about the key?” she whispered.

“Not yet,” Mason said, a light of triumph in his eyes. “I know what happened now, Della. Give us the breaks, and we’ve got this case in the bag. First, make him prove we were in that apartment.”

Linn said, “I will now call Miss Shirley Tanner to the stand.”

The young woman who advanced to the stand was very different from the disheveled and nervous individual who had been so angry at the time Mason and Della Street had pressed the button of Apartment 702.

“Your name is Shirley Tanner, and you reside in Apartment 701 of the Mandrake Arms Apartments?”

“Yes, sir.”

“And have for how long?”

She smiled, and said, “Not very long. I put in three weeks apartment hunting and finally secured a sublease on Apartment 701 on the afternoon of the eighth. I moved in on the ninth, which explains why I was tired almost to the point of hysterics.”

“You had difficulty sleeping?”

“Yes.”

“And on the morning of the tenth did you have any experiences which annoyed you—experiences in connection with the ringing of the buzzer in the apartment next door?”

“I most certainly did, yes, sir.”

“Tell us exactly what happened.”

“I had been taking sleeping medicine from time to time, but for some reason or other this night I was so nervous the sleeping medicine didn’t do me any good. I had been unpacking, and my nerves were all keyed up. I was physically and mentally exhausted but I was too tired to sleep.

“Well, I was trying to sleep, and I think I had just got to sleep when I was awakened by a continual sounding of the buzzer in the apartment across the hall. It was a low, persistent noise which became very irritating in my nervous state.”

“Go on,” Linn said. “What did you do?”