The alcove itself opened on one side upon the terrace and upon the other into a large butler's pantry.

The arrangement was obviously designed so that, if necessary, one could pass directly from the terrace to the downstairs service quarters or the second floor of the house without going through the living-room, and so that trays could be carried up from the pantry by the side stairs without using the main staircase.
The middle pair of French windows were open, forming a double door.
Miss Cornelia went over to them--shut them--tried the locks.

Humph! Flimsy enough! she thought.

Then she turned toward the billiard room.
The billiard room, as has been said, was the last room to the right in the main wing of the house.

A single door led to it from the living-room.