Vadim Perelman’s new film, “The Life Before Her Eyes,” combines two separate narratives that follow a single woman named Diana. In one, she’s a free-spirited (to put it somewhat mildly) adolescent played by Evan Rachel Wood; in the other, a grown wife, mother, and art history teacher, played with surprising gravity by Uma Thurman. Young Diana primarily fills the emotional vacuum created by her absent single mother with a broad spectrum of bad-girl behavior. After her biology teacher shares the old anatomical saw about the percentage of moisture in the human body, Diana’s strait-laced friend, Maureen (Eva Amurri), counters that Diana is probably “72% bong water.”

Adult Diana has left the self-destructive excesses of youth in the past. Though she hasn’t made good on her vow to leave her sleepy, photogenic hometown, she has acquired a handsome college professor husband named Paul (Brett Cullen), and together they have produced a daughter as picture-perfect as they are.

But there is an appalling event that both divides and unites Diana’s past and future. As they pause in their high school bathroom to dish about Maureen’s recent first date, Diana and Maureen are silenced by the off-screen sound of automatic gunfire. Moments later, they are looking down the barrel of an MP5 submachine gun, which appears to be the movie weapon of choice for young psychos in school shootings. Relishing his last few moments of control over life or death before the SWAT team drops him, the girls’ gun-wielding classmate explains that he is only going to kill one of them, and asks them to decide which.

Using parsed-out fragments of this post-Columbine, “Sophie’s Choice” scenario as a kind of narrative adhesive, “The Life Before Her Eyes” details Diana and Maureen’s pre-gunpoint relationship, as well as grown Diana’s survivor guilt and recurring post-traumatic stress coming to a head on the anniversary of the killings. It initially seems that the tragedy 15 years ago pulled Diana out of a behavioral tailspin and pushed her to adopt Bible-reading Maureen’s moral compass. But as cracks begin to show in Diana’s marriage and her daughter begins to exhibit signs that she’ll follow in her mother’s rough and rowdy ways, Diana, like Kurt Vonnegut’s Billy Pilgrim and so many movie protagonists since, comes unstuck in time. The only way she has of reconciling the unreality of her “perfect” yet unearned second chance is to return to the fateful moment that she, Maureen, and their tousle-haired tormentor shared.

Ms. Wood, whose high forehead, large, thoughtful eyes, and slender, girlish figure will likely earn her scripts about teenage characters into her 30s, invests young Diana with an affecting natural intelligence. Likewise, Ms. Thurman deftly externalizes the inner turmoil of a woman who won’t be let off the hook by circumstances well beyond her control.

But the breakout performance in “The Life Before Her Eyes” occurs behind the camera. After the cloddish excesses of “House of Sand and Fog,” a film that delivered NPR sound-bite story pieties with abusively adamant film grammar and lazy, simplistic dramatics, Mr. Perelman’s comparatively gentle directorial handprint in “The Life Before Her Eyes” borders on the revelatory.

The film’s narrative bluff is easy to spot in the distance, but its impact is nevertheless impossible to dodge and, once it has passed, it is equally hard to shake. “We all dream of being a child again, even the worst of us,” says the Mexican bandit patriarch in Sam Peckinpah’s emotionally acute 1969 film “The Wild Bunch” — “perhaps the worst of us most of all.” “The Life Before Her Eyes,” a film that could just as accurately have been billed as “Occurrence at Owl Creek High” after the Ambrose Bierce short story it ultimately resembles, takes the opposite view. As children, the film points out, the least happy of us dream of being an adult. The bitter and touching message secreted inside this brightly colored sugar pill of a film is that making it out of childhood alive is never a sure thing.