Sixty-five million years ago, something slammed into the Yucatan Peninsula and ended the age of dinosaurs, leaving behind the Chicxulub crater as evidence. This documentary uses that impact as its starting point, then builds a scenario around a new comet on a collision course with Earth. Geologists and astronomers walk through the physical evidence buried in the K-T boundary layer, the iridium spike and shocked quartz that first tipped scientists off to an impact rather than a slow extinction. From there the film models what a modern strike would actually do: the fireball, the shockwave flattening forests for hundreds of miles, the dust and soot lofted high enough to block sunlight and cool the planet for years afterward. Interviews with researchers who study near-Earth objects explain how such comets are tracked today and what options, if any, exist for deflecting one. The film treats the dinosaur extinction as a case study for a still-open question: whether humanity would fare any better than they did.