Today more than two million people live in style in the hottest, driest part of North America, the Sonoran desert. They are the last in a long line of settlers - Spanish missionaries, American cowboys and farmers - who all tried to impose a new way of life on the fragile nature of this desert. Unlike the plants and animals which have evolved spectacular ways of coping with these arid lands, the newcomers seeking the sunshine of Phoenix, Arizona, are only now beginning to face the harsh reality of living here on the edge of existence.