Eleven-year-olds Tripti Kapoor, a feisty "word nerd" from Massachusetts, and Sam Cohen, a shy, imaginative, budding geologist from California, are both miserable at Camp Dilloway, a summer camp in upstate New York. On the last night of camp, they follow a shooting star to a quiet creek. There they find two silvery rocks glowing in the night. They each take one home, and their long-distance friendship begins.

It's soon clear that these are no ordinary rocks. They seem to move on their own, get strangely hot, and even take over Tripti and Sam's thoughts! Inspired by their mutual love of their favorite book series, The Dragon Gems, they dub the rocks Opal and Jasper, after the Dragon Gems in the books.

But others are interested in the stones too--including the owner of Camp Dilloway, who hides a secret of his own. Tripti and Sam must crack the Dragon Gems' code and keep them out of Dilloway's clutches, all while navigating the rocky road of middle school friendships and learning to stand up for what is right.