Silently the boys raised the ladder to the casement. It was a little too short, but a person stepping from the window and hanging on the sill with both hands could just reach the topmost rung. Frank went up. He threw the signal stones at the glass. They rattled like hail. The next instant the sash went up. A head was stuck out.
"Is that you, Frank?" a voice whispered.
"Yes, father! Can you come down?"
"Right away. Is everything safe?"
"Everything. Be careful, you will have to make a long step."
"I can do it. I have done more difficult things than this on my travels."
Frank's heart beat high with hope, for he knew from the sound of his father's voice that the prisoner was sane.
Cautiously Mr. Roscoe crawled from the window. He hung by his hands until his feet touched the top rung of the ladder. Then, with Frank preceding him, he went down and was soon on the ground.
"These are my chums, father," said Frank.
"I can't tell how I thank you for getting me from that terrible place," said Mr. Roscoe. "But we must hurry away. The guard will make his rounds soon, and if he sees my room empty the alarm will be given."