Tom turned to a door that led to the kitchen of the house. The door was shut, and he tried in vain to open it. The others were behind him and they, too, tried to open the barrier.

"Must be locked from the other side," said Tom. "Come on out the way we came in. Gracious! Isn't that awful stuff that is burning?" he added, for the vapor now filled the room completely.

In sudden alarm the four boys turned back toward the folding doors through which they had entered the dining-room. To their consternation, the doors were tightly shut.

"Who shut these?" asked d.i.c.k as he tried to open one of the doors.

"I didn't," said Sam.

"Neither did I," added Tom.

"n.o.body touched the doors!" e.j.a.c.u.l.a.t.ed Stanley. "It must be some of the ghost's work."

"Nonsense!" answered d.i.c.k sharply. "Somebody shut the doors--and locked 'em," he added after trying both. "Hi, you!" he called. "Open these doors, and be quick about it!"

"Thou fool, to come here!" exclaimed a hollow voice from the other side of the doors.

"It's the ghost! I said it was!" said Stanley,

"It's somebody fooling us," answered Tom. "Open the door, or we'll smash it down!" he added in a loud voice.

Instead of a reply there came a weird groan and then the rattle of some heavy chains. Stanley turned pale and began to tremble, but the Rovers were not much impressed.

"We don't believe in ghosts, so you might as well let us out!" cried d.i.c.k. "That stuff you set on fire is smothering us!"

At this there was a murmur from the next room, but what was said the prisoners did not know.

"Come on, let us get out of a window!" cried Tom. His head was commencing to swim, and he could hardly see.

"Tha--that's it," murmured Sam. "Say, I'm--I'm--going--" He did not finish, but sank to the floor in a heap.

"Sam has been overcome!" cried d.i.c.k in horror.

"Oh, if only we hadn't come here!" groaned Stanley. "I--the window--I--am--smothering!" He took another step forward and then fell. d.i.c.k tried to pick him up, but went down also, with his brain in a whirl and strange lights flashing before his closed eyes.

Tom was the last to be overcome. He reached a window, only to find it tightly locked. He smashed the gla.s.s, but could not open the blinds.

Then he went down; but before he closed his eyes he saw the door to the kitchen open and several masked faces appeared. He tried to say something, but the words would not come, and then all became a terrible dark blank around him.

For about half a minute after Tom went down nothing was done. Then the door to the kitchen was thrown wide open and four figures appeared.

All wore sheets and masks.

"You are sure it won't kill any of them, Parwick?" asked a voice that sounded like Jerry Koswell's, and which was far from steady.

"Yes, I'm sure," answered the voice of a stranger. "But we don't want to leave them in this room too long. Take 'em below."

"If we get found out--" said another, and one could readily recognize Flockley's voice.

"We won't get found out," put in a fourth person. It was Larkspur.

"Come ahead, and don't waste time here."

With great haste the masked ones picked up the three Rovers and Stanley and dragged them into the kitchen of the old house. Then one after another the unconscious ones were taken down into a dark and musty cellar and placed on some straw.

"Now to fix up the evidence!" cried Koswell. "We must be quick, or it may be too late!"

For all of a quarter of an hour the three Rover boys and Stanley Browne lay where they had been placed on the moldy straw. They breathed with difficulty, for the strange vapor still exercised its influence on their lungs.

At last Sam stirred and opened his eyes.

"Wha--what's the matter with me?" he murmured, and then sat up.

He could see next to nothing, for the cellar was dark. His head ached keenly, and he could not collect his senses. He also felt somewhat sick at the stomach.

"d.i.c.k! Tom!" he called. "Where are you?"

There was no reply, but presently he heard somebody stir.

"Don't--don't kill me!" murmured Stanley. "Take the ghosts away!"

"Stanley!" called Sam. "Whe--where are we?"

"Who--who is tha--that?" stammered Stanley, sitting up.

"It is I--Sam!"

"Whe--where are we, Sam?"

"I--I don't know."

"My head is go--going around like--like a top."

"So is mine. Tom! d.i.c.k!"

"Is that you, Sam?" came faintly from the elder Rover as he opened his eyes.

"Yes. Where is Tom?"

"Here, I guess, beside me." d.i.c.k shook his brother. "Tom! Tom! Wake up!" he cried. But Tom continued to lay quiet with his eyes tightly closed.

Sam was feeling in his pocket for a matchbox, and presently he brought the article forth and made a light. He was still so dizzy he could scarcely see about him. Stanley had fallen back again, gasping for breath.

By the dim light afforded by the match the two brothers looked at Tom.

He was gasping in a strange, unnatural fashion.

"I believe he is choking to death!" said d.i.c.k hoa.r.s.ely. "Air! He must have air!" He arose unsteadily to his feet. "Bring him here!"

And he made for a closed cellar window with all the strength he could command.