Source: movieclipsTRAILERS Youtube channel
The film starts with Adam telling the story of his planet, unique from other planets as it is the only one that has dual gravity. Two planets live next to one another. The gravity has 3 rules:
1 - All matter is pulled by the gravity of the world that it comes from, and not the other.
2 - An object's weight can be offset by matter from the opposite world (inverse matter).
3 - After some time in contact, matter in contact with inverse matter burns.
The two worlds are separated. While Up is rich and prosperous, Down is poor. Up buys cheap oil from Down and sells electricity back to Down at much higher prices. Going Up is strictly forbidden and the only connection between the worlds is through the company "TransWorld".
Jim Sturgess as Adam
Kirsten Dunst as Eden
Timothy Spall as Bob