Experts suspect that the dinosaurs were wiped out after a city-sized asteroid smashed into the Gulf of Mexico causing a huge crater. But until now, they haven't had any proof. In a world first, evolutionary biologist Ben Garrod joins a multi-million pound drilling expedition into the exact spot the asteroid hit to get hard evidence of the link. The team overcomes huge obstacles as it attempts to drill 1,500 metres beneath sea level to pull up rock from the Chicxulub crater. Meanwhile, paleopathologist Professor Alice Roberts travels the globe meeting top scientists and gaining exclusive access to a mass fossil graveyard in New Jersey - believed to date from the same time the asteroid hit. Alice also treks by horseback across the remote plains of Patagonia, to see if the effects of the asteroid impact could have wiped out dinosaurs across the world - almost immediately.