66 million years ago a seven-mile-wide asteroid collided with Earth, triggering a chain of events suspected of ending the dinosaurs' reign. But experts have long debated exactly what happened when the asteroid struck and how the giant beasts met their end. Now, scientists have uncovered compelling new clues about the catastrophe - from New Jersey to the wilds of Patagonia, and an international expedition of scientists has drilled into the impact crater off the coast of Mexico, recovering crucial direct evidence of the searing energy and giant tsunami unleashed by the asteroid. Join NOVA as scientists piece together a chillingly precise unfolding of the Earth's biggest cataclysm, moment by moment. And discover how our early mammalian ancestors managed to survive and repopulate the Earth.