“It’s hinged at the top I think. Find the little button and press on it. Then when you hear a click push on the panel. Only push easy or you’ll take a tumble the way I did.”

In a minute Rosanna had located the button. She pressed upon it as she had seen Penny do. Then as the lock clicked, she cautiously pushed against the panel. Light as was her touch the sector of wall swung instantly back and she stepped through the opening. So concerned was she over Penny that she failed to hear the panel close behind her.

At first Rosanna could see nothing. Then as her eyes became accustomed to the gloomy interior she made out a long flight of stone steps leading downward into inky blackness.

She felt reassured when Penny grasped her hand.

“Come on, Rosanna! Isn’t it exciting? Let’s explore!”

“Oh, it’s too dark!” Rosanna whispered nervously. “What if we should run into that dreadful man—the organist?”

“Well, perhaps it would be wiser to go back for a flashlight,” Penny conceded. “Only we mustn’t let Mrs. Leeds or Max Laponi suspect what we’re up to. We must keep this discovery strictly to ourselves.”

She returned to the head of the stairs but although she groped her hand carefully along the wall she could find no hidden button or spring which controlled the panel. By this time Rosanna had grown frightened.

“Don’t tell me we’re locked in!”

Penny forced herself to speak calmly. She knew that it would never do to let Rosanna realize that she too was alarmed.