“Where are the others?” asked Teddy, as he reached Billie’s side.

“They’re down looking for the ghost,” answered Billie, as she ran down the stairs in front of them.  “They sent me to get you boys, and I found you gone.  Mrs. Gilligan,” she added, with a hysterical giggle, “has the broom and Laura has the poker.”

“Maybe we’d better stop on the way and gather up a few bedposts,” suggested Ferd, as they took the last flight of stairs on a run and landed in the lower hall.

“Hello, did you find anything?” sang out Chet, as the girls, looking scared but valiant, came out to meet them.  “Where’s Mrs. Gilligan?”

“Inside,” said Violet.  “There isn’t a thing to be seen any more than there was the other night.  I’m absolutely positive now that it must be a ghost.”

“Well, if it is, he’s got a sense of humor,” said Mrs. Gilligan, rising from her knees where she had been peering into the corner behind the piano.  “I’ve heard of all sorts of spirits, but I never heard of one who insisted upon playing the piano in the dead of night.”

“He must have been a musician in his life time,” suggested Chet.  “That’s the reason he comes and haunts the piano.”

“Well, I don’t see why he doesn’t choose a regular piano to haunt,” said Billie, feeling irritable because she was very sleepy and had been very much frightened.  “It’s bad enough for a live person to play, let alone a ghost.”

“And where could it have gone?” wondered Laura, her eyes big and dark with excitement.  “The minute we heard the noise—­I guess we’re sort of listening for it even in our sleep—­we jumped up and came down here while Billie went to call you boys.  It was playing almost up to the minute we came into the room.”

“And maybe we weren’t afraid to go in!” said Violet, with a shudder.  “I don’t know how we ever got the courage.”

“Well, you only came because Mrs. Gilligan and I went ahead with the broom and the poker,” sniffed Laura.

“Was it playing when you came down the stairs?” asked Chet, interested.  “And did it stop as soon as you entered the room?”

“Yes,” it was Mrs. Gilligan who answered this time.  “And it was good for him he did.  I’ve lost enough sleep through the miserable rascal and I was just ripe for a tussle.”

“I don’t blame him for running,” said Teddy, with a chuckle.

“But where did he go?” asked Laura again.  “We were sure that we’d see something—­goodness knows what—­when we turned the corner of the room.”

“And all we saw was a—­a large amount of nothing at all,” added Violet, wide-eyed.

“Perhaps,” suggested Ferd, with a chuckle, “the aeroplane we heard belonged to him—­”

“A ghost’s aeroplane,” murmured Billie, smothering another hysterical chuckle.

“And when you girls came in he just soared skyward and went off in it.”

“It’s funny we never thought of that,” said Teddy scornfully.