Robert De Niro is "Jacknife," a nickname given to him because of a penchant for wrecking trucks in the Army. But he's more often called "Megs," a shortening of his last name - Megessey.

The film opens with Megs returning to an industrial town he left 15 years earlier to reacquaint himself with Dave (Ed Harris), a buddy with whom he served in Vietnam.Unfortunately Dave is in an alcoholic stupor he's been unable to pull out of for several years, suffocating not only himself but also his sister Martha (Kathy Baker), a high school biology teacher with whom he lives.

Basically "Jacknife" has Megs finding himself a catalyst of sorts for changes in the lives of Dave and Martha. Dave finds himself propelled more rapidly downward, leading him closer to self-destruction, unless he can be turned around, and Martha blossoms as she and Megs begin a tentative love affair.

Storywise, that's pretty much it, except for a sad secret Dave has buried in his psyche but which tortures him by rising to the surface when he sees Megs again. The rest of the film is slightly wacky Megs popping in and out of the lives of Dave and Kathy, whether they want him to or not.

The script has intelligent dialogue and real-life situations played out with humor and compassion, but there are questions left open about the characters, edges that seem rough and dimensions that could use some filling in.

But because the three actors - De Niro, Harris and Baker - are so good, they lend the proceedings more depth than they deserve.

De Niro is almost doing a sequel to "The Deer Hunter," playing Megs as a returned Vietnam vet still suffering aftershock some 15 to 20 years after his wartime experiences. He's all blue-collar gruffness and sweet sincerity, stumbling over himself in an effort to be what he thinks Martha will like, and trying to help Dave get back on his feet.

Likewise, Baker plays Martha as someone who thinks she knows herself well, but who has no idea how to act with someone as down-to-earth and yet edgy and goofy as Megs.

And Harris, who could have played Dave as a sappy sot who is little more than pitiful, manages to conjure up dignity and intelligence behind those bloodshot eyes.

In short, the audience comes to care a great deal about all three - and that makes up for a lot in a movie like this.

"Jacknife" doesn't really pose any revelations toward our understanding of the Vietnam veteran, but it doesn't wallow in self-pity either, though there is plenty of opportunity. It simply recognizes as real the problems of people who have suffered personal trauma and offers a glimmer of hope for them to come through it and make life better for themselves and those they love.

It is rated R for some violence, discreet (and comic) sex, nude photographs in a garage and scattered profanity.