“Well, think it over.” Biff made a vicious left swing at his imaginary sparring partner. “Be sure and let me know.”

Then he chased the invisible enemy down the road and was soon lost to sight around the bend.

“He’s going to miss one of those wild swings of his some day and knock himself out,” prophesied Joe. “I never did see a fellow so crazy about boxing.”

“He’s good at it. Still, that’s not a bad idea he has about camping during the Christmas holidays. We’ll talk it over with Chet.”

“Sure.”

The boys went on and in a short time they came to the Jefferson house. It was a large, gloomy mansion, set back some distance from the road, and when the boys went up the walk, which had been swept and shoveled clear of snow, it was with a quickening sense of anticipation.

They rang the bell.

“We’ll soon know what Mr. Jefferson wants to see us about,” said Frank.

The door opened.

The housekeeper, a prim, angular woman, regarded them silently for a moment.