The big-buzz Sundance movie "An Education" is set in 1961, and as acolytes of "Mad Men" can tell you, that's no insignificant detail.

It's a year that finds the West poised on the edge of enormous change - as a woman in "A Serious Man" (also set in the 1960s) puts it, it's a time when forward-looking people can take advantage of "the new freedoms."

Change is in the wind in "An Education," the story of an exceedingly bright prep schoolgirl named Jenny (Oscar nom shoo-in Carey Mulligan) who's working hard to pass her Oxford entrance exams, and in idle moments imagining the brave new world that her generation senses is just around the corner.

Jenny, 16 and full of dreams, lies on the floor of her room listening to French singers and smoking French cigarettes. At school, she quotes the French existentialists, and tries very hard to tolerate the bumbling advances of the awkward boys who are understandably smitten by her looks, intellect and poise. (These scenes are very funny, as you might expect from a Nick Hornby script, no matter how grave the drama eventually gets).

Nearly everyone, in fact, is smitten by this gifted girl - her hovering parents (Alfred Molina), her starstruck friends, her most attentive teacher (Olivia Williams) who recognizes a once-in-a-lifetime prize pupil, someone with the brains and the good timing to go places she never could.

Then someone else falls for Jenny - a much older man named David (Peter Sarsgaard), who has a fancy car, money, modern taste and stylish friends (Dominic Cooper, Rosumund Pike).

He begins to date her, posing to her parents as an educational benefactor. Jenny is intoxicated, a little by the champagne, a lot by the glamour - art auctions, jazz clubs, even jaunts across the pond to Paris.

The viewer is not so much intoxicated as alarmed - this is a 16-year-old going off with a much older man, and not just any man, but Sarsgaard, one of the movie's great slippery characters - the sexual chameleon of "Kinsey," the simmering killer of "Boys Don't Cry." When he presses Jenny for a sexual relationship, it's hair-raising, in part because of his age, in part because of the way he infantilizes her.

The relationship raises many red flags, none of which seem to catch the attention of Jenny's parents. When she turns 17, they're as happy to see her married as they are to see her at Oxford. And razor-sharp Jenny is blind to his flaws, even when he admits to them.

The movie's arguable lapses in credibility have bothered some critics, but it's worth noting the screenplay is based on a memoir by British journalist Lynn Barber, and it has the feel of real life - clumsy human missteps often fall under the heading of Hard To Believe.

And there is something very believable in the way Jenny's growing self-awareness becomes a liability - she IS exceptionally bright and mature, and she bathes in the attention - even David's friend begins to covet her, to the chagrin of his vapid blonde arm candy (Pike is quietly great in this role).

The way one character bounces off another in "An Education" is endlessly interesting. No role, no matter how small, is thrown away. Williams has only a few minutes, but makes a huge impression as the wary teacher who sees Jenny trading a limitless future for something as disposable as a man, and tries to intervene. Her pleading advice - "go to Oxford, no matter what" - is the heart of the movie.

She helps make "An Education" one of the great stay-in-school movies in recent memory, and an unusual one - it doesn't target the "at risk" kid, but the girl who thinks she knows everything, and has the test scores to prove it.

Jenny tells her headmaster that in 1961, it's no longer enough to educate students - you must tell them why you're doing it.

The answer is implicit - Barber's memoir covers 1961, but was written decades later, by a witness who survived the stifling '50s and also the freewheeling '60s and '70s.

It's no longer enough to liberate students, you must prepare them for liberation.

So go to college, no matter what.