s alone in his empty house in the countryside. Mrs. Plunkett lives next door and cares for him in the absence of his parents. Hank and his classmates, Ruby Basher and Sam Benedetto, win their Grade 8 Science Fair, and the prize is summer camp in the Rocky Mountains.

Meeting up at the camp with three other science fair winners, Julianna Wong, Oz Solomon, and Zebi Little Crow, they get lost during a terrible storm while chased by a grizzly bear. They stumble into a hidden cave with walls covered in multiple drawings of dinosaur teeth.

Hank and his friends use their small flashlights to move more deeply into the dark underground. They make their way into another cave where they discover Mascon, a 403-year-old seer. He knew they would find him, enabling him to send them on a quest into a secret valley where the world's last dinosaurs still lived. He gives each of them specially heightened powers of taste, touch, sight, hearing, and smell, as well as intuition-all which can keep them alive if they work together.

Their incredible adventure leads them into battle with beasts they thought were extinct!

They meet Golden Eyes, queen of the pterodactyls, whose mission is to keep them alive. But is she clever enough to help all six young explorers find the cave of kings and escape from the secret valley?