Roughly 250 million years ago, something killed off 95 percent of life on Earth in a geological blink, the worst of the planet's five mass extinctions and the only one severe enough to nearly empty the oceans and continents at once. The film follows scientists piecing together what happened from rock records in Siberia, Antarctica, and Greenland, layers that preserve the chemical fingerprint of the die-off itself. Attention centers on the Siberian Traps, a vast outpouring of volcanic rock whose eruptions are the leading suspect, and researchers use radiometric dating and geochemical analysis on samples from these sites to pin down how fast the extinction actually happened and whether volcanism alone can explain a kill this total. Interviews with geologists and paleontologists lay out competing lines of evidence and where they still disagree. The program treats the Permian extinction as an open scientific problem rather than a solved case, building its account from field evidence rather than dramatization, and closes with the event's unsettling relevance: something wiped out almost everything once, and the geological record says it can happen again.