Adventure seekers will find plenty of thrills in Allende's first novel for young readers. When 15-year-old Alexander Cold is sent to stay with his eccentric, gruff grandmother, Kate, while his mother is being treated for cancer, he is more than a little reluctant to accompany Kate on a writing assignment in South America to search for a legendary nine-foot-tall "Beast." However, once the expedition down the Amazon begins, Alexander's doubts are pushed out of his mind by more immediate concerns, such as keeping an eye on two suspicious members of the party: a native named Karakawe and Mauro Cari as, a wealthy entrepreneur. After Alexander's mysterious encounter with a caged jaguar, another teen, Nadia, explains its importance to him, and begins calling Alexander "Jaguar." This marks the beginning of their somewhat surreal journey: the two teens are kidnapped by the "People of the Mist," a tribe possessing the power of turning invisible, and enter a mountain to discover the mythical city of El Dorado and the enigmatic "Beasts." Reluctant readers may be intimidated by the thickness of this volume, but the plot moves at a rapid pace, laced with surprises and ironic twists. The action and outcome seem preordained, cleverly crafted to deliver the moral, but many readers will find the author's formula successful with its environmentalist theme, a pinch of the grotesque and a larger dose of magic. Ages 10-up.