You probably already know that The Invention of Lying takes place in a world where deception doesn't exist. Mankind never developed the ability. Everyone is 100 percent truthful all the time -- not because they feel obligated to, but because the concept of lying has literally never occurred to them. If someone came along who could lie, well, his power would be almost limitless. Everyone would believe everything he said. The skill of lying would be what scientists call an evolutionary advantage.
In a strange way, that's sort of what The Invention of Lying is about: the forward progression of the human species. Co-written and directed by Ricky Gervais and newcomer Matthew Robinson, the film has its wacky moments reveling in the absurdity of a world where no one lies, some of which feel like a Saturday Night Live sketch or an improv show. ("Your suggestion is: 'a world where no one lies'! The scene is: a blind date! Go!") But it's also surprisingly thoughtful, even tender, in the way it considers love, relationships, and God.
For what you might not already know about the film is that lying isn't the only thing absent from this world. There's no religion, either. No one believes in God -- that word, like "lie," is never used -- because no one ever thought to make him up. (The movie's view, one infers, is that God is imaginary and thus wouldn't be part of a world where no one ever fabricated.) The Man in the Sky, as God comes to be known, is the invention of our hero, Mark Bellison (Gervais), a loser who suddenly finds that he can say things that aren't true.