After their parents are lost in an accident, thirteen-year old twins Grace and Marty are whisked away to live with their Uncle Wolfe--an uncle that they didn't even know they had. The intimidating Uncle Wolfe is an anthropologist who has dedicated his life to finding cryptids, mysterious creatures whose existence has never been proven.

Just as the twins and their uncle are getting to know one another, Wolfe finds out that his nemesis, Dr. Blackwood, is headed to a Congolese jungle to poach a dinosaur and her clutch. Wolfe has to mobilize his team immediately if he wants to beat Blackwood to the jungle. And his team does not include the twins.

But Grace and Marty aren't easily left behind. With breakneck daring, they literally drop into the Congo. Through a series of perilous adventures, they uncover long-buried secrets about their own identities and that of their uncle. Now the twins must play a high-stakes game, where the prize is a dinosaur egg, and the penalty is death.