After repeatedly running into an eccentric old man, Johnny senses that something strange will happen to him this summer. His cousins remind him that his great-grandfather had mysteriously disappeared many years earlier in the woods surrounding the trading post. When the children discover their great-grandfather's journal, the temptation is too great, and they decide to retrace the steps he took before his mysterious disappearance.
In The Crystal Pool, Johnny, Ben, and Patty learn much about themselves, their family history, a new world they never expected to find, and the beautiful, mysterious power that lies behind it all. Eventually their journey leads them to a wondrous place to which few have traveled, and from which no one has returned. To survive their quest, the three cousins will have to summon courage and faith they never knew they had and uncover once and for all what lies beneath The Crystal Pool.