There was a knock at the door.
"Come in," cried Frank.
The door opened, and a boy about seventeen years of age entered the room. He was a slender, delicate-appearing fellow, but he had a good face and steady eyes.
"Hurrah!" cried Frank. "Here is my preserver! Professor Scotch, permit me to introduce you to Mr. Walter Clyde."
The professor held out a limp hand to the boy, saying:
"Excuse me if I do not rise. Frank just robbed me of strength by telling how you saved his life by derailing an express train and killing forty passengers."
Clyde was quick to catch on. A faint look of astonishment was followed by a smile, and he said:
"Mr. Merriwell is mistaken."
"Ha!" cried the professor. "Then you denounce the whole story as false?"
"I said Mr. Merriwell was mistaken—but thirty-nine passengers were killed," said the newcomer, who had caught the end of Frank's yarn.