[spoiler]An alien race sneaks onto Earth, disguises themselves as humans, and takes the place of every political leader in the world. Then, another alien race which is fighting the aforementioned one tells a man about what is going on, named David. So David has to kill all the worlds 'leaders'. There is a lot more to the plot, but I don't want to give too much away.[/spoiler]

[spoiler]Sounds cool.[/spoiler]