"Go to your rooms," commanded Professor Grimm. "I will look into
this."

"I wish he hadn't seen us," said Jack, when his two chums had taken
him to his dormitory.

"Why?" asked Sam. "Where's the harm?"

"I have a sort of queer feeling that something is going to happen,"
Jack replied. "I want to finish out the term with a good record, for
my aunts' sakes. If there are any pranks played tonight, Grimm will
be sure to suspect me."

"Don't cross a bridge until it trips you up," said Sam. "Now, let's
have a look at that ankle."

They found it was not as bad as Jack had feared.

"I've got a bottle of arnica somewhere," he said. "I think I'll put
some on."

His chums found the bottle, and were rubbing the swelling with the
medicine when there came a knock at the door.

"Who's there?" asked Jack.

"Professor Grimm," was the reply. "I want to see if you are really in
your room."