Plot: In 1982, when the bodies of 3 women were discovered beneath the surface of Seattle's Green River, no-one realised that it was the beginning of an extraordinary killing spree that would baffle police for 19 years. The 'Green River Killer' would become the most prolific serial killer in US history, claiming the lives of more than four dozen victims, but it would take until 2001 before DNA testing solved the mystery of his identity