Charlie Thorne and the Lost City (Charlie Thorne Series #2)

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 Islands. That is, until she's approached by the mysterious Esmeralda Castle, who ...