There is abundant evidence that comets and asteroids have bombarded Earth and other planets in the past, and it is statistically probable that objects from space will continue to hit the Earth in the future. This documentary looks at the history of past impacts and near-misses (some of which have been caught on camera!), the likelihood of an impact large enough to endanger human life on Earth, the effects of such a catastrophic collision, and what (if anything) we can do to prevent it.