A group of eccentric aliens confers a human being with the power to do absolutely anything, as an experiment.

Some aliens, who travel from planet to planet to see what kind of species inhabit them, come to Earth. And if humans are, according to their standards, decent, they are welcomed to be their friend. And if not, the planet is destroyed.

To find out, they choose one inhabitant and give that person the power to do whatever he or she wants. And they choose Neil Clarke (Simon Pegg), a teacher who teaches the special kids. He is constantly being berated by the headmaster and is attracted to his neighbor, Catherine (Kate Beckinsale), but doesn't have the guts to approach her. But now he can do anything he wants, but has to be careful.