Helena is the high school junior who knows all the angles.
Heading into the summer before senior year, she realizes her junior boyfriend John, perhaps the cutest boy ever to attend the high school, is losing interest in her, she plans her revenge.
She breaks up with him in the nicest most 'mature' way. He's so impressed, even a little guilty-feeling.
Helena's father is a criminal attorney. She finds one of his pro bono clients--a tough teenage streetwalker named Agnes. Helena arranges probation in return for watching over Agnes.
Thus begins the Pygmalian makover to end all makeovers.
The slutty, potty-mouthed, drug-addled little girl is transformed into the image of purity, virtue and style.
When Agnes transfers to Helena and John's expensive high school in the fall as a freshman (complete with doctored transcript), everyone thinks she's from a convent school!
Helena maneuvers John into dating Agnes, and they're the biggest couple since--well, since John and Helena herself.
Everyone's impressed with how totally un-jealous Helena is. She gets major points for maturity, even though she's not dating anyone and it's her senior year.
Little do they know that at the senior prom, Helena plans on allowing Agnes's probation officer to come and find her violating her probation--she's planted a joint in Agnes's borrowed designer bag.
But when the probation officer shows up with drug-sniffing dogs, everything changes.
No one seems to care that Agnes was a skanky 'ho' only a year earlier. It's what she's done since that they care about.
No one's ashamed or embarrassed--except Helena herself.
And Helena sees how John is ready to go to jail himself on Agnes's behalf, Helena realizes John actually loves Agnes, loves her in a way Helena and John never loved each other.
So Helena takes the drug rap herself and is toted off to jail on her prom night.
She's even ready to call Daddy to come bail her out, when the whole senior class shows up with the bail money.
All's forgiven and a lot of valuable lessons were learned, plus a lot of skimpy costumes worn and dialogue spoken.
(Yes, it's a remake of Robert Bresson's Les Dames du Bois du Boulogne, which is in turn based on Denis Diderot's Jacques le Fataliste. Sue me.)
--E. R. O'Neill