Quietly Craig went to the door which led to the next room.  It was, of course, locked also.  He listened a moment carefully.  Not a sound.  Quickly, with an exclamation of satisfaction, he opened that door also and went into 509.

This room was much like that in which we had already been.  He opened the hall door.

“Watch here, Walter,” he directed, “Let me know at the slightest alarm.”

Craig had already taken the brace and bit from the bag and started to bore through the wall into room 511, selecting a spot behind a picture of a Spanish dancer—­a spot directly back of her snapping black eyes.  He finished quickly and inserted the detectascope so that the lens fitted as an eye in the picture.  The eye piece was in Room 511.  Then he started to brush up the pieces of plaster on the floor.

“Craig,” I whispered hastily as I heard an elevator door, “someone’s coming!”

He hurried to the door and looked.  “There they are,” he said, as we saw Elaine and Mary rounding the corner of the hall.

Across the hall, although we did not know it at the time, in room 540, already, Long Sin had taken up his station, just to be handy.  There he had been with his servant, playing with his two trained white rats.

Long placed them up his capacious sleeves and carefully opened the door to look out.  Unfortunately he, was just in time to see the door of 509 open and disclose us.

His subtle glance detected our presence without our knowing it.

Hastily picking up the brace and bit and the rest of the debris, and with a last look at the detectascope, which was hardly noticeable, even if one already knew it was there, we hurried into 511 and shut the door.

Kennedy mounted a chair and applied his eye to the detectascope.  Just then Mary and Elaine entered the next room, Mary opening the door with a regular key.

“Won’t you step in?” she asked.

Elaine did so and Mary hesitated in the hall.  Long Sin had slipped out on noiseless feet and taken refuge behind some curtains.  As he saw her alone, he beckoned to Mary.

“There’s a stranger in the next room,” he whispered.  “I don’t like him.  Take the money and as quickly as possible get out and go to my apartment.”

At the news that there was a suspicious stranger about, Mary showed great alarm.  Everything was so rapid, now, that the slightest hesitation meant disaster.  Perhaps, by quickness, even a suspicious stranger could be fooled, she reasoned.  At any rate, Long Sin was resourceful.  She had better trust him.

Mary followed Elaine into the room, where she had seated herself already, and locked the door.

“Have you the money there?” she asked.

“Yes,” nodded Elaine, taking out the package of bills which she had got from the bank during the half hour delay.

All this we could see by gazing alternately through the detectascope.