The ads for "Kramer vs. Kramer" project a misleading image of domestic tranquility. A snapshot reveals Dustin Hoffman, Meryl Streep and Justin Henry, a winsome 6-year-old, grouped for a cozy family pose. This picture of contentment is underscored by the legend, "There are three sides to this love story."

Given the story that unfolds on the screen, this claim is a bit of a whopper, either deliberately ironic or wildly disingenuous. The movie congratulates itself for an even-handed approach; but it's actually a triumph of partisan pathos, a celebration of father-son bonding that astutely succeeds were tearjerkers like "The Champ" so mawkishly failed.

The title characters are an estranged couple: Hoffman's Ted Kramer is introduced as a bustling New York advertising executive preoccupied with his career, Meryl Streep's Joanna Kramer as a frustrated spouse who walks out on Ted and their son Billy in the opening sequence. Dubiously contrived yet undeniably absorbing and affecting, "Kramer vs. Kramer" depicts how this instant marital collapse leads to a climactic custody battle and transforms Ted into a better man.

Despite its inherent bias, carried over from the original novel by Avery Corman, "Kramer vs. Kramer" rakes up complicated emotions about profoundly important relationships. Moreover, it implies that these relationships may require a certain heroic effort to preserve or sustain in a middle-class culture that subjects people to a great deal of centrifugal, status-seeking, family-breaking pressure.

While it's apparent that screenwriter-director Robert Benton feels duty-bound to record Joanna Kramer's rationalizations and even give them a gentlemanly benefit of the doubt, the dramatic emphasis is always on the dilemma of the abandoned Ted.

We see what the struggle to remain a breadwinner while also raising a kid does to and for Ted Kramer. It's an intimately touching, improving process. dThe sentimental heart of the movie is the illusion of turbulent but loving father-son rapport that seems to evolve between Dustin Hoffman and little Justin Henry.

Ted and Billy forge a stronger relationship out of big fights and quiet conversations, out of their increased intimacy and emotional dependence. When Billy injures himself in a playground accident, Ted dashes across half of Manhattan to get his stricken son to the emergency ward. Ted's new maternal duties cause him to neglect his paying job and then get the sack. Swallowing his pride, he fights to obtain a lower echelon job at a lower salary. The longer Joanna is away, the more heroic Ted's paternal exertions become.

Emotionally, Joanna is out of the picture, and one could argue that she never quite gets into it. The movie opens with an exquisitely overcomposed shot of Streep leaning over to kiss the sleeping child goodbye on the night Joanna has already resolved to walk out. Although Benton's cinematographer, Nestor Almendros, became famous working with Francois Truffaut and Eric Rohmer and won the Oscar last year for "Days of Heaven," the formality and concentration are obviously Bergmanesque.

The visual ambience of this pensive maternal image is echoed throughout the production in Benton's apparent preference for arranging things neatly -- indeed, a little too neatly. I'm certain Hoffman will be the front-runner for this year's best-actor Oscar, and what I like best about his vivid, urgent, sentimental performance was its need to disrupt the neatness, to express the authentic emotional messiness and turmoil of a concerned parent's relationship with his child.

What Hoffman does is always effectual and inevitably adds up. Streep, however, is in a no-win position. Obliged to suggest the troubled psyche of a young woman who leaves her child in the opening sequence, she vanishes for an hour or so and then returns to provoke a climatic conflict by recklessly threatening the stability of a relationship we've grown to value.

The strain shows on her performance.Mrs. Kramer may have justifiable reasons for abandoning her marriage -- that issue remains reasonably and realistically debatable -- but she never has a respectable reason for abandoning her kid.

Moreover, Streep doesn't really have a scene with the little boy. They're together only twice: at the beginning when the child is sleeping, and later when Ted delivers Billy for a court-ordered afternoon outing with Joanna upon her return. But we don't see how mother and son may have spent this reunion, theoretically loaded with poignant and painful interplay. However, this missing element is consistent with the fleeting, indirect characterization of Joanna.

While she's been away -- allegedly discovering self-esteem through therapy in California and a career designing sportswear -- the audience has been sharing the trails of her husband and growing enormously fond of her kid.

Consequently, sympathizing with Joanna's position seems to require reading volumes into Streep's melancholy or stressful expressions.

Moreover, when Hoffman reads her letter of explanation to the boy, it's difficult to escape the conclusion that Dear Mrs. Kramer is a dim-witted victim of some of the sorriest cultural cant lately in vouge:

"Mommy has gone away . . . I have gone away because I must find some interesting things to do for myself in the world. Everybody has to and so do I. Being you mommy was one thing and there are other things and this is what I have to do. I did not get a chance to tell you this and that is why I am writing to you now, so you can know this from me. Of course, I will always be your mommy and I will send you toys and birthday cards. I just won't be your mommy in the house. But I will be your mommy of the heart . . ."

Your mommy of the heart, my aching backside. Taken straight from the novel by Corman (who also supplied the movies with "oh, God!"), this has to be the most excruciating epistle inflicted on a defenseless child since Ginger Rogers read the letter from her G.I. Joe in "Tender Comrade" that drove James Agee into a sarcastic fit.

Although Kramer is supposed to be genuinely touched by his wife's letter (the least convincing moment of Hoffman's performance), the reading is adroitly manipulated to enhance the relationship between father and son. When the kid, understandably perplexed, asks if mom left home because of something he did (a very accurate psychological detail), the father assures him it wasn't and generously takes all the blame upon himself.

If not a model mother, Ted Kramer grows into an admirable mother-substitute. He even becomes close friends with the neighbor lady -- Jane Alexander as the separated mother of two -- who is introduced as Joanna's best friend.

Alexander is one of several deftly chosen and deployed supporting players. Benton also enjoys excellent performances from George Coe as Hoffman's employer, Howard Duff as his attorney and Jobeth Williams as a romantically inclined colleague, whose overnight dalliance with Kramer leads to the film's funniest confrontation.

Paul Sylbert's sets for Kramer at home and at work look impeccably habitable and evocative, free of the excessively "classic" formality imposed by much of the cinematography and the choice of Vivaldi for background music. Capable as he is, Benton may pigeonhole himself as a kind of highbrow middlebrow if he persists in arranging so much compelling domestic conflict in such tidy baroque packages.

The clash of Benton's temperament with Hoffman's probably brought genuine creative tension to "Kramer vs. Kramer." Hoffman keeps trying to make the material spill over while Benton endeavors to keep it neat and incisive. Instinctively, you feel that Hoffman has the right idea. "Krmaer vs. Kramer" is a fine effort, but a little more spillage in the right places might have made it unforgettable.