The Library Kids Talking Stones is the 4th of a 7 book series that continues with the children learning the importance of messages in stone by studying ancient artifacts at the Chicago Oriental Museum and then studying the history of Mount Rushmore. The crystal mission heats up in Mexico and Peru as the children must battle an evil sorcerer to retrieve the fourth and fifth crystals. At the end of the mission, Scott's father returns for a surprise visit and reveals a secret about himself.