“It opens on a small porch and a flight of steps to the sunken garden. The lower hall of the guest wing lies through the arch here.”

With a humorous glance at his impassive companion Landis parted the curtains and they stepped through to find themselves looking down a long hall at right angles to the library. Landis dropped the curtains behind him. In the billiard-room, the two young men exchanged glances and went on with their game.

The hall which the detectives now faced was richly carpeted. Six doors opened into it, three on the left, one at the end and two on the right. All six were closed.

“Help!” Landis grumbled. “This place is like a hotel! Well, what are all these rooms?”

Graham’s nervous answering smile acknowledged, almost gratefully, this human touch of exasperation.

“They’re bachelor guest rooms,” he explained, “two on each side with a bath between. That door at the end leads outdoors to the garage. We use this hall a lot coming in and out.”

“Anybody using the rooms?” asked Bernard dryly.

“Those two chaps in the billiard-room are quartered here. Russell, the big fellow, has the far room on the right, facing the front of the house. Allen has the far one on the left. The nearer rooms are unoccupied so far as I know.”

“What’s the extra door down there?” Landis cut in.