Winding stone steps led downward.
The submarine chamber!
Harry remembered what Marquette had told him about that experimental room, below the level of the lake. It was the only outlet from the cellar. Arlette must be down there.
Without a moment’s hesitation, Harry descended the steps.
He came upon a huge metal door, located on a landing; the door was opened toward him. Beyond it were more steps, that led into a small, stonewalled room.
Harry’s flashlight showed a mechanical device opposite the steps — presumably the torpedo tube. Then he saw the torpedoes themselves, standing against the wall — heavy, metal shells, more than six feet in length.
Now his light revealed something on the floor. There lay Arlette, pitifully helpless — bound and gagged.
Harry drew his revolver, and rushed down the stone steps. He flashed the light in every direction.
There was no one else in the room. The man who had captured Arlette had gone.
Harry quickly cut the cords that bound the girl. He released the gag. Arlette had fainted; now she revived and tried to speak. Harry watched her lips; then saw that they framed a warning.