It’s rare that a film -- especially a studio film -- does this: goes so far in a direction you weren’t even expecting it would go in at all that the shock of it is doubled. It’s easy to see why none of the promotional material for The Invention of Lying even begins to hint at how sneakily subversive the film is -- it had me literally gasping at its daring, and how that daring steals up on you -- because it goes to a place that will shock many moviegoers. What starts out as a kind of comedic episode of The Twilight Zone has, by the halfway mark, turned a corner into a satire on an aspect of humanity that some take so much for granted they won’t even have realized it could be open to such a commentary.

Star Ricky Gervais wrote and directed Lying with first-time filmmaker Matthew Robinson, and from the get-go he takes a bracingly self-aware tack with his tale. It all occurs in a world in which no one has the capacity to lie, and Gervais dispenses with the need to examine how people can even talk about the concept of a lie if they’ve never encountered such a thing before, which does present a bit of a parsing problem, by consciously framing this as a fable he is relating to an audience -- us -- who are already familiar with the idea. His meta-omniscient narration (which takes on an extra dollop of irony later on) informs us as the film opens about the barriers and limitations of the people of this clearly unworkable world, and how it will all change when the character he plays will accidentally stumble across the notion of The Lie. It frees the story from worrying too much about plausibility and leaves it to concern itself with the philosophical conumdrums it will invariably encounter, which is the entire point of the exercise.

And an uproarious exercise it is, reveling in a Monty Python-esque outrageousness to explore the simplest consequences of the world’s first lies and grandest extrapolations that can be spun from the possibilities of lying. Gervais’s (Night at the Museum: Battle of the Smithsonian, Ghost Town) Mark Bellison is a schlubby writer... of nonfiction, of course: there is no fiction in this world, and the movies Mark writes are the baldest, plainest kind of documentary. Not only does no one in Mark’s world lie, but everyone is constantly spouting whatever thoughts are crossing their mind. What we would consider a simple polite request such as “Are you doing okay?” -- one that typically, in fact, demands a response of “Yes, thanks,” even if that is less than honest -- in this world gets a reply of, “Usually. Some days I stay in bed eating and crying.” Instead of keeping her mouth politely shut at the prospect of a date with Mark, his dream girl, Anna McDoogles (Jennifer Garner: Ghosts of Girlfriends Past, Juno), instantly reveals that she’s not attracted to him because he’s kinda fat and not very handsome.

At first -- even before Mark discovers it is indeed possible to say something that is not true -- Gervais and Robinson use this ever-truthful world to send up office politics and romance and the lies that grease both types of human interaction. (Rob Lowe [Thank You for Smoking, View from the Top] and Tina Fey [Ponyo, Baby Mama] are hilarious are Mark’s coworkers, who are constitutionally unable to hide their disdain for him.) But even as Mark is still marveling at the awesome power suddenly at his behest now that he can lie, the film turns slyly bitter and biting: a street person holds up a sign that reads, “I don’t understand why I’m homeless and you’re not.” And we begin to understand how beige and boring this world is without the power of human imagination to enliven it. We begin to notice things like this: On the wall of Mark’s apartment is a dartboard... and next to it, a painting of dartboard. If a thing cannot be seen in this world, it cannot exist, not even in a painting. (The production design by Alex Hammond is so subtle and so clever that it will likely go unnoticed, but it contributes powerfully to the overwhelming blandness of this world.)

And then, the true uncomfortable brilliance of The Invention of Lying begins to show its face. Even as the film turns into something downright seditious by asking probing questions about the lies that we, in our world, may be dealing with on a daily basis without ever realizing they may well be lies, it also recognizes a positive side to our ability to deceive and conceive: not only do we brighten our world and enrich our lives with how we use our imaginations, but -- the film wonders -- is it wrong to tell a lie if it makes someone happy? If it isn’t wrong to tell a lie for that reason, is there a grander scale upon which happy-making lies are wrong?

The film doesn’t answer the question, only raises it. But a vigorously inventive and smartly aggressive question it is. And merely asking the question in the particular way that it does, and by skewering the particular target that it does, makes this comedy that is genuinely -- and delectably -- dangerous.