A unique metaphor for the "empty nest" syndrome, "Running on Empty" is perhaps the most powerful, moving film of the year so far, and certainly will be at the front of the line for Oscar contenders.

Powerhouse performances from Christine Lahti, Judd Hirsch and River Phoenix drive the literate screenplay by Naomi Foner, who also wrote the less successful "Violets Are Blue." And director Sidney Lumet, who has given us many fine films, has never been more in control.The story has Arthur and Annie Pope (Hirsch and Lahti) on the run from the FBI. As young radicals they organized the bombing of a government-funded napalm laboratory to protest the Vietnam War. The building was supposed to be empty, but a janitor was blinded in the blast.

So the Popes have been on the run for 15 years, living "underground," moving from city to city, changing names and identities along the way with the help of a community network of former radicals.

It has become a routine, a way of life, but that doesn't make it a comfortable one - especially for their two sons Danny and Harry (Phoenix and young Jonas Abry).

Danny, in particular, is having trouble coping. At 17 he's on the verge of graduating from high school and an exceptional musical talent has surfaced. Unbeknownst to his parents, Danny auditions for Julliard scouts, and they are very taken with him.

But he knows he cannot apply for admission because his records are not available. The past is finally catching up with him and doesn't know where to turn. Should he pursue his talent, integrate into mainstream life and perhaps never see his parents again? Or should he stay with the family he loves?

To further complicate matters, Danny has fallen in love with Lorna (Martha Plimpton), the daughter of his current high school music teacher.

Even with all of this, however, Danny is reluctantly ready to make the sacrifice and stay with his parents and brother. Not that his father is giving him much choice. For Danny to leave, Arthur tells Annie, "is unacceptable."

But Annie can see that they are going to have to let Danny go and allow him to begin a normal life.

It is upon this central conflict that "Running on Empty" spins its story, allowing us to identify with the feelings if not the circumstances of its characters.

And because of the nature of this story, Lumet and Foner are able to tell it in the trappings of a suspense film, explore the conflict of '60s sensibilities in the '80s and use the situation as a metaphor for the problems of the modern nuclear family.

The film builds slowly and at first it seems to be a family version of "Bonnie and Clyde" as the foursome stays one step ahead of the law. But gradually it becomes more complex and it isn't long before the audience is hooked.

The performances are fabulous. The main focus is on River Phoenix and he gives a multi-layered performance that is brooding, yet never aloof; quiet, yet quite telling. As his father, Judd Hirsch is also marvelous, saying much without words. Martha Plimpton is also quite good as the sassy, volatile Lorna, who, despite her more ideal family circumstances, is much more of a rebel than Phoenix.

As for Christine Lahti, this is her eighth movie, and she has yet to be in a box office winner. It's been said by others, but Lahti is perhaps America's greatest unknown actress. She is wonderful in this picture and, hopefully, may finally get the recognition she deserves.

"Running on Empty" is certainly one of the year's best films, but don't go in without some Kleenex. It is rated PG-13 for profanity.