(This video is no longer available for streaming.) Host Neil deGrasse Tyson joins a team of investigators hot on the trail of a mass murderer—one that knocked off its victims 250 million years ago when it wiped out the majority of life on our planet. Long before the dinosaurs, at the end of the Permian Period, something triggered Earth's most profound mass extinction and reset the evolution of life on this planet.
The clues suggest it was not the result of an asteroid impact, the likely cause of the dinosaur extinction later on. Could deadly bacteria have set off a chemical chain reaction that poisoned the Permian seas and atmosphere? As well as a fascinating whodunit, the story is a cautionary tale on the threat posed by modern-day global warming.