In this sequel to the New York Times bestselling Charlie Thorne and the Last Equation--which #1 New York Times bestselling author Chris Grabenstein called "a real page-burner"--Charlie searches for Charles Darwin's hidden treasure in South America. Charlie Thorne is a genius. Charlie Thorne is a fugitive. Charlie Thorne isn't even thirteen. After saving the world, Charlie is ready to take it easy in the Galapagos...