Life along the Rio San Miguel has remained relatively unchanged for the last 300 years. David Yetman and Mexican ecologist Alberto Burquez trace the river through Sonora, Mexico, to see how life has adapted to its unpredictable flow. The trip begins in Magdalena de Kino, with a stop at Father Kino's monument, before heading south to the city of Cucurpe. With the assistance of local resident Don Beto Cruz, Yetman surveys the local river vegetation thriving during the summer monsoon. Further south the landscape becomes more modern as local farms give way to sprawling cities.