Roughly 252 million years ago, something wiped out up to 96 percent of marine species and 70 percent of terrestrial vertebrates in what paleontologists call the Great Dying, the most severe mass extinction the planet has recorded. This film traces the event through the fossil and geological record, laying out the numbers: 57 percent of all animal families gone, 83 percent of genera gone, and a recovery that took as long as 10 million years before ecosystems rebuilt themselves. It walks through the competing explanations researchers have proposed, from gradual sea-level and climate shifts to sudden shocks, weighing evidence for two separate extinction pulses rather than one clean event. The Siberian Traps, a stretch of volcanic activity that burned coal and gas on a continental scale, get treated as a leading suspect alongside methane released from the ocean floor and a possible impact event. Expert interviews and reconstructed prehistoric scenes carry the argument, building toward the same open question the fossil record leaves behind: what combination of causes could kill nearly everything at once.