“I thought of that,” Penny said. “And since he can’t possibly know how the secret doors works, he’ll wait until after that part of the evening’s entertainment is over. Then he’ll try to sneak back and go down into the room while we’re unmasking.” She chuckled. “In that case, he’ll walk right into our trap. After the last guest has left, Phil can stay behind and hide in the alcove. If Mr. X sneaks back and goes down into the room, all Phil has to do is fasten the door from the outside, once Mr. X is safely down the stairs. Then we can call the police, for obviously no honest person would go into the secret room without our permission.”
“I object,” Jimmy said. “According to that scheme, we’ll catch Mr. X, but we still won’t know what he was trying to steal.”
“I agree with Jimmy,” Phil said. “So instead of hiding in the alcove after the guests have all seen the secret room, I’ll hide down in the room itself. Behind the black draperies you’ve hung on the walls. If he sneaks back, I’ll stay there until after he’s got whatever he’s trying to get. Then at the point of my gun I’ll make him turn it over to me and—”
Penny interrupted with a frown: “I still don’t like the idea of your being down in the room alone with someone who may be a dangerous criminal, Phil.”
“Oh, Penny,” Marjorie cried impulsively, “Phil can take care of himself. Besides, Mr. X won’t have any idea that he’s hiding behind the black curtains. Also,” she added, “what Mr. X wants may not be in the secret room after all.”
“That’s true,” Penny admitted reluctantly.
“Then the scheme is this,” Peter said, summing it up. “If you and Marjorie see a stranger sneak upstairs before the unmasking, you’re to report at once to Phil, Jimmy and me. We’ll follow him and catch him in the act. If no one does anything suspicious, Phil will remain in the secret room after the guests have seen it. Pat, who will open the door, will close it when everyone has left the alcove. Then we’ll all go into the big room for the unmasking and wait until Phil signals that he has caught a rat in his trap. You can do that, Phil,” he finished, “as we already agreed, by banging on the door.”
And so the final arrangements were made. But Penny, as she hurried upstairs with Marjorie to dress for the occasion, knew that Peter was worried. He didn’t like the idea of Phil being locked in the secret room with Mr. X any more than she did.
“But,” she realized suddenly, “Phil won’t be locked in after all. Even though we may deliberately play into Mr. X’s hands by showing him how to get into the secret room, he won’t know where the spring is that closes the door on the other side.”
And, as Marjorie pointed out while they helped each other with their costumes: “The whole thing may be a flop. We don’t know for sure that there is anything valuable hidden in the Lodge, or that Mr. X will be among those present tonight.”