Outside her home in Michoac n, Mexico, grows eight-year-old Isabel's greatest treasure: an oyamel tree. Every autumn, a miracle happens-for Isabel's tree is the wintering place for thousands upon thousands of monarch butterflies that migrate from the north. When they flutter down to roost, they transform Isabel's tree into La casa de las mariposas-The House of Butterflies. But this wonder is in danger of disappearing forever. Isabel's family is poor,...