Sometimes great results arise out of considering a simple "what-if." For director Alfonso Cuaron and his film "Gravity," the idea seems to have been: "What if you made a cliffhanger ... with no cliffs?"
Set in the freefall of space, "Gravity" is a heart-stoppingly suspenseful survival flick of man vs. atmosphere. Sandra Bullock and George Clooney star as astronauts Ryan Stone and Matt Kowalski — he the grizzled vet, she the hesitant first-timer — in Earth orbit and outside their space shuttle doing some routine repair work. They're enjoying their final space walk before returning to Earth when they get a sudden order from NASA to return to ship; a Russian missile strike on a satellite has sent a cloud of debris racing towards them — at 30,000 kph.
Things get hairy about 10 minutes in, and it doesn't let up till the end; there's no point in revealing anything further about the plot except to say it doesn't involve aliens, clones or evil computers. Rather, Cuaron seeks to depict the terror of an accident in this unforgiving environment, where life is measured in the seconds of oxygen left on your tank and rescue is impossible.