City of the Beasts by Isabel Allende

When Alexander Cold's mother falls ill, the fifteen-year-old is sent to stay with his eccentric grandmother in New York. A tough and prickly magazine reporter, Kate Cold takes Alex along with her on an expedition to the Amazon to verify the existence of the fierce, gigantic, legendary creature known as the Beast. Joining them on their adventure are a celebrated anthropologist; a local guide and his daughter, Nadia; a doctor; and a local entrepreneur. But not everyone's intentions are pure—and dangerous discoveries await Alex and Nadia as they embark, with the aid of a jungle shaman, on an epic journey into the realm of the mythical Beasts of the Amazon.

City of the Beasts is the first book in an extraordinary trilogy by Isabel Allende, one of the world's most acclaimed authors.