Water puts out fire. That is supposed to be rule number one of the physical world. Yet Ohio's Cuyahoga River didn't just fail to extinguish flames, it actively started them, catching fire at least 13 times.

This episode traces the Cuyahoga's journey from a sacred indigenous sanctuary to the darkest depths of industrial pollution and on to a remarkable ecological rebirth. We explore the strange glacial geography behind its crooked path, the toxic decades when the water oozed rather than flowed, and how a small 1969 fire with no surviving photos still managed to ignite the modern American environmental movement.

• How retreating Ice Age glaciers carved the river's bizarre U-turn and where the name really comes from
• The grim 1968 descriptions of a biologically dead river covered in inches of floating oil
• Why the histor ...