"You are appealed to to help lay a ghost and find a missing girl," broke in Betty. "But, oh, the last is most important! Please come and get Mollie out!"
"Yes, I guess that is the most important. You can tell me about it later. But I surely was astonished to meet you girls again—glad of it, though. Now for the prisoner. Lead the way, Miss Nelson."
Flashing her lantern, the other girls keeping at her side, and Cousin Jane bringing up in the rear, Betty advanced to the locked door. Mr. Blackford tried the knob, and then called:
"Stand back, whoever is in there. I'm going to burst this door open!"
Grace cried out.
"Quiet!" commanded Betty. "It is the only way."
Mr. Blackford placed his shoulder down near the lock. There was a cracking and splintering of wood, and the door suddenly flew open with a crash.
"Mollie! Mollie!" cried Betty, as she flashed the rays of her lamp inside.
But the room was empty! Mystified, the girls, their chaperone and Mr. Blackford, stared about it. No Mollie was there!
"But I'm sure she was thrust into this room by that figure in white," declared Betty. "We all saw it."