DIVORCE HAS become as American as vallum: as available for the asking from some store front Perry Mason as its pill counterpart from some would be Freud. But though valium is a personal affair between a neurotic and his deadened senses, divorce offers something for the whole family to go crazy about.

Kramer vs. Kramer, for all its exposure of the pangs of divorce for Mom and Dad, portrayed the children of divorce as the emotional equivalent of furniture, just another trinket to split in the final settlement. Firstborn looks at the American family in the aftermath of divorce and examines the furniture that must grow up with "new relationship" Skillfully avoiding the artistic temptation to transform the Livingston family into Every Family and the film into The Social Statement, Firstborn draws us into a painful and complex story that may be one of this year's best films.

Fifteen year old Jake Livingston (Chris Collet) lives a seemingly ordinary suburban life, exposed even to that symbol of the suburban high school: The Coach. "This could be the most important thing you learn in school," coach tells his lacrosse following, which includes Jake. "I've got to teach you how to dry yourself after the shower. One time I had a bad case of athlete's foot. One night I woke up screaming. The infection had spread from my feet up to my crotch and that's how I lost one of my testicles."

The Livingston children encounter a different crisis at home. Jake Livingston and his ten year old brother Brian (Corey Haim), rushing through a quick breakfast, meet "Sam." Where's Mom? "Asleep" Sam says, and introduces himself awkwardly as Mom's friend.

Jake and Brian could love Sam. Sam knows the surest path to befriending the two comes through a credit card. For Jake, there is the motorbike; for Christmas, Jake is not impressed, "He's an asshole," Jake says.

And FROM the mouths of sassy teenagers comes the truth. Somewhere between Sam's smooth talk about opening up a security firm, somewhere between promising to open up a restaurant and "make things work out," something seems to go wrong, Cocaine, nearly as American as divorce, enters the scene and blasts Mama Livingston out of reality. Jake and Brian meet Sam's strange friends, find Mom and Sam crashed out on the couch after some coke blizzard and learn that Sam is moving in. "Just like that?" Jake asks. "We live here too?". Don't we ger any say?"

Watching the world almost exclusively through Jacke's warm but confused eyes, Firstborn makes Jake into a Superkid, faced with Herculean tasks while still in the Clearosil mindset. Mom seems intent on bringing down her life on top of the entire family: his real Dad is nothing more than a dinner partner on the way to a seven a.m. business trip; his girlfriend just wants to have fun. His English teacher warns, "Watch it Jake, your works not so good that you can afford to get on my bad side.

Jake appears torn between the two great adolescent impulses: rebellion and brooding. Jake the brooder downs wine with his girlfriend, races across town on his motorbike, and walks everywhere with a permanent glaze of confusion and despair. Jake the rebel plays the quintessential smart-ass, letting out sarcasm faster than he can understand it. This Jake mouths things like "Don't ever touch me or my brother again," even as Sam appears ready to smash him into the wall. This Jake assures his brother's principal there will be no more fights "Because I promise."

Jake the Brooder and Jake the Smart Ass we know well. Those Jakes are adolescence according to Hollywood. Unable to solve problems, they either sulk them or Sherry Lansing, largely responsible for Kramer vs. Kramer introduce a different teenager here, a teenager who can't just drink away his problems or race away on his motorbike. His brother, saying don'tcare where we go-let's just go, offers the route many would choose.

With all its dimensions and contradictions, Jake's character entails an unusual challenge given the Hollywood trend to treat its young male leads as Calvin Klein underwear models and the general willingness of its leads to seem even devoid of that much acting ability. Much of the success of Firstborn comes from Christopher Collet's masterful performance as Jake, offering even in his sassiest scenes a glimpse into the conflict tearing at him. How disappointing, then, that Firstborn must nonetheless include the de rigeur weightlifting scenc in Jake's bedroom.

As Chris' chief antagonist. Peter Weller plays Sam with scary perfection. Weller, who most recently portrayed the brain suergon-rqckstar-world hero in Buckaroo Bonsai, switches easily but believably from a dreamy drifter to a dangerous madman, with much of the same charge seen in last year's Star 80.

Overshadowed by her two co-stars. Terri Garr nevertheless proves her versatility here. Often cast as the most adorable character Garr here makes Jake's mom something more pathetic than just a middle aged woman in need of a good shampoo.

Firstborn, like few recent films, offers a happy reminder that acting can make a film. With Ghostbusters. Murray, Ackroyd, and Ramis make a comedy even without a plot. Here, Collect, Weller, and Garr make a storing film into one of the best. Firstborn does not try to make a social statement by inserting treatises into its characters mouths, rattling off stats about divorce or runaway kids, in the style of some cheap television production. Instead Firstborn is a personal statement offering less pat answers than just a painful and powerful reminder to give pause.