Slim reached out and tugged away at the post again, but nothing happened.

Then he got hold of the carved head and began to twist it and it turned under his hands. There was a click, faint, but audible to the eagerly listening ears, and the landing began to slide smoothly back into place.

In a moment the opening was closed, and the landing was apparently a solid piece of carpentry.

"Whoever invented that was a genius!" exclaimed Justice in admiration.

"And all the while we were trying to find a secret pa.s.sage through the walls by tapping on the panels! If it hadn't been for Slim we could have spent all the rest of our lives looking for it and never would have found it, for we never in all the wide world would have thought of twisting the head of that stair post. Slim, you weren't born in vain after all."

"See if you can make it open up again," said Sahwah.

Slim twisted the head of the post, and presently there came the now familiar click and the floor slid out with uncanny quietness.

"Let's go down!" said the Captain, going to the edge of the opening and looking in.

"What's down there?" asked Katherine.

"Nothing but s.p.a.ce," replied the Captain, straining his eyes to peer into the darkness, "at least that's all I can see from here. Give me your flashlight, Slim, I'm going down."

Slim handed him his pocket flash and the Captain began to descend the ladder. He counted twelve rungs before he felt solid footing under him.

He found himself in a tiny room about six feet square, whose walls and floor were of stone. The top was open to allow the pa.s.sage of the ladder.

The Captain figured out that he was standing level with the floor of the bas.e.m.e.nt and that the s.p.a.ce above the opening at the top of the little room was the s.p.a.ce under the stairway. There was a door in the outside wall, next to the ladder.

"What's down there?" asked Sahwah from above.

"Just a little place with a door in it," replied the Captain, retracing his steps up the ladder.

"The pa.s.sage isn't inside the house at all," he reported when he reached the top. "It's _outside_. There's a door down there that probably opens into it. I'm going to get my coat and see where the pa.s.sage leads to."

"We'll all go with you," said Sahwah, and it was she who went down the ladder first when the expedition started.

The Captain came next, carrying a lantern he had found in the kitchen. At the bottom of the ladder he lit the lantern. The first thing its light fell upon was a broken gla.s.s jar, lying in a corner, and from it there extended across the floor a bright red stream. Sahwah recoiled when she saw it, but the Captain stooped over and streaked his finger through it.

"Paint!" he exclaimed. "Red paint."

"Oh!" said Sahwah. "It looked just like blood. Why-that's what must have made the footprints on the stairs! The man must have stepped in this paint! He came in through this pa.s.sage!"

The other three had come down by that time, and they all looked at each other in dumb astonishment. How clear it all was now! The footprints beginning under the stair landing-the mystery connected with the entrance of the intruder-they all fitted together perfectly.

"The paint's still sticky," said the Captain, examining his finger, which had a bright red daub on the end. "It must have been spilled there quite recently."

"The burglar must have spilled it himself," said Katherine.

"But how on earth would a burglar know about this secret entrance?"

marveled Sahwah.

The others were not prepared to answer.

"Maybe Hercules told somebody," said Justice.

"But Hercules doesn't seem to know about it himself," said Katherine.

"He _says_ he doesn't, but I'll bet he does, just the same," said Justice.

"Hercules wouldn't tell any burglar about this way of getting into the house!" Sahwah defended stoutly. "He's as true as steel. If anybody told the burglar it was somebody beside Hercules."

"Maybe the burglar discovered the other end of the pa.s.sage himself, by accident, just as we did this end," said Slim.

"Come on," said the Captain impatiently, "let's go and see where that other end is."

"Wait a minute, what's this," said Justice, spying a long rope of twisted copper wire hanging down close beside the ladder. This rope came through the opening above them; that was as far as their eyes could follow it.

Its beginning was somewhere up in the s.p.a.ce under the stairs.

"Pull it and see what happens," said Slim.

"I bet it works the slide opening from below here," said Justice. He gave it a vigorous pull and they heard the same click that had followed the twisting of the stair post. In a moment the light that had come down through the opening vanished, and they knew that the landing had gone back into position. Another pull at the rope and it opened up again.

"Pretty slick," commented Justice. "It works two ways, both coming and going. A fellow on the inside could get out, and a fellow on the outside could get in, without the people in the house knowing anything about it."

"Are you coming now?" asked the Captain. "I'm going to start."

He opened the door in the outer wall as he spoke. It swung inward, crowding them in the narrow s.p.a.ce in which they stood. A rush of cold air greeted them. The Captain held the lantern in front of him and peered out into the darkness.

"There are some steps down," he said.

He stepped over the threshold and led the way. Six steps down brought them to the floor of a rock-lined pa.s.sage, a natural tunnel through the hill.

"Carver Hill must be a regular stone quarry," said Justice. "All the cellar walls of Carver House are made of slabs of stone like this, and so is the foundation."

"There are big stones cropping out all over the hill," said the Captain.

"It's a regular granite monument. What a jolly tunnel this is!"

"And what a gorgeous way of escape!" remarked Justice admiringly.

"But what need would there be of an underground way of escape?" asked Katherine wonderingly. "What were the people escaping from?"

"This house was built in the days of the Colonies," replied Justice sagely, "and the Carvers were patriots. That probably put them in a pretty tight position once in a while. No doubt they concealed American soldiers in their home at times. This pa.s.sage was probably built as a means of entrance and escape when things got too hot up above. British troops may have been quartered in the house, or watching the outside.

What a peach of a way this was to evade them!" he exclaimed in a burst of admiration.

"I wish I'd lived in those times," he went on, with envy in his tone.

"They didn't keep fellows out of the army on account of their throats then. What fun a soldier must have had, getting in and out of this house, right under the nose of the British! Suppose they suspected he was in the house and came in to search for him? He'd just turn the post on the stairs, and click! the landing would slide open and down the ladder he'd go and out through this pa.s.sage. The enemy would never discover where he went in a million years."

"Come on, let's see where this pa.s.sage comes out," urged the Captain, and started ahead with the lantern.

The pa.s.sage sloped steeply downward, with frequent turns and twists.

"We're going down the hill," said the Captain.

"Whoever heard of going down the _inside_ of a hill," said Sahwah.

"It's like going through that pa.s.sage under Niagara Falls," said Slim, "only it's not quite so wet."