In this children's film about the values of fighting air pollution, a young singing group (Regaliz) is joined by other pre-teens to discover why all the birds have deserted Barcelona -- and what will bring them back again? When it appears that the culprit is the city's smog-filled air, the youngsters decide to take matters into their own hands. Their civic calling is subsequently lightened by snappy dialogue and a few musical numbers. The children organize protests, they convince the mayor to help out, they struggle with their parents, and even set up tree houses in a public park as their new residences. Their activities come to a climax when one of them is injured falling out of a tree house, and the boy's father -- an industrial mogul -- starts taking the problem of air pollution to heart. Maybe there is some hope for the return of the birds after all. ~ Eleanor Mannikka, Rovi