When the alien Drej destroy the Earth, Cale (voiced by Matt Damon) is among the few survivors. While his father flies a mighty starship, the Titan, to safety, Cale ultimately falls in with a construction crew until a friend of his father's comes looking for him fifteen years later. It's not a social call, either: Cale holds the key to the very survival of the human race.
Not that you'll care. The strength and the weakness of Titan AE (it stands for After Earth) is in its animation which is by turns breathtaking and atrocious. The backgrounds and settings are imaginative and sometimes gorgeous, more often so well done that they are near photographic. But every character is drawn in two dimensions - both literally in the animation and figuratively in the story.
The effect is like constantly switching channels between an expensive science fiction movie and the best that Saturday morning children's television can offer.
The script does attempt to reverse some standard SF cliches such as the heroes overpowering guards who should know better, but no dialogue is memorable, at least not without shuddering.
It really is that bad.There are good ideas in the plot, but none of them come to anything and several are ignored in favour of a simplistic ending. True SF fans and artists may get a lot out of the animation but it will take an eye for graphics and a very tolerant mind.
If you need a clinching argument, note that the studio that made "Titan AE" has since been closed down.