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 has a code she knows only Charlie can decipher. In 1835, Charles Darwin diverted his ship’s journey so he could spend ten months in South America on a secret solo expedition. When he returned, he carried a treasure that inspired both awe and terror in his crew. Afterward, it vanished, never to be seen again… But Darwin left a trail of clues behind for those brave and clever enough to search for it. Enter Charlie Thorne. In a daring adventure that takes her across South America, Charlie must crack Darwin’s 200-year-old clues to track down his mysterious discovery—and stay ahead of the formidable lineup of enemies who are hot on her tail. When an ancient hidden treasure is at stake, people will do anything to find it first. Charlie may be a genius, but is she smart enough to know who she can trust?

This eBook edition of "Doctor Thorne" has been formatted to the highest digital standards and adjusted for readability on all devices. When their father dies, Doctor Thomas Thorne and his younger, ne'er-do-well brother Henry are left to fend for themselves. Doctor Thorne begins to establish a medical practice, while Henry seduces Mary Scatcherd, the sister of stonemason Roger Scatcherd. When Scatcherd finds out that Mary has become pregnant, he seeks out Henry and kills him in a fight. While her brother is in prison, Mary gives birth to a girl and Doctor Thorne persuades her to accept the generous offer, promising to raise his niece, naming her Mary.