She picked up a small latch-key from the desk.

"This is number 11, isn't it?" she asked quickly.

"No! Number 11 is the flat immediately overhead," he told her.

She appeared unconvinced.

"But I opened the door with this key," she declared.

"Mr. Barnes and I have similar locks," he said. "The fact remains that
this is number 9, and number 11 is one story overhead."

She drew a long breath, presumably of relief, and moved a step forward.

"I am very sorry!" she declared. "I have made a mistake. You must please
accept my apologies."

He stood motionless in front of the door. He was pale, clean-shaven, and
slim, and in his correct evening clothes he seemed a somewhat ordinary
type of the well-bred young Englishman. But his eyes were grey, and his
mouth straight and firm.

She came to a standstill. Her eyes seemed to be questioning him. She
scarcely understood his attitude.

"Kindly allow me to pass!" she said coldly.

"Presently!" he answered.