The Secret of Skull Mountain

by Franklin W. Dixon

  Although he did not realize it at the time, Frank was speaking the truth. The Hardy boys were closer than they knew to the mystery connected with The Sign of the Crooked Arrow.

  Now, standing on the crest of Skull Mountain, the young detectives, their father, and their friends stared down Tarnack Valley. Soon the mouth of the prehistoric tunnel would be walled up forever. Then the thin sheet of water which now covered the valley would become a deep lake.

  Bob and Dick smiled happily as they visualized it, while Frank and Joe exchanged grins.

  “Guess we’re thinking the same thing,” said Frank.

  “We sure are,” Joe replied. “Now we’ll have plenty of water in the swimming pool!”