Aquatic ecologist Dr. Zeb Hogan teams up with kayaking expert Trip Jennings and a team of Brazilian scientists to tackle the Rio Roosevelt in western Brazil. They'll battle the river's deadly rapids in an effort to complete a comprehensive survey of one of the Amazon's most remote jungle rivers, and discover what monster fish are lurking beneath the surface of this 400 mile-long river. Pressures like logging and dams are believed to be destroying critical fish habitat throughout the region. His journey is an important look at what might be lost if these pressures reach the pristine Rio Roosevelt.