"The Squid and the Whale," Noah Baumbach's semi-autobiographical movie about the breakup of his family, feels like it was penned in the filmmaker's own blood -- it flows that directly from firsthand experience. At times its scrutiny is so embarrassingly ruthless, you can imagine the real Baumbachs squirming and twitching away somewhere.

In actuality, Baumbach grew up in Park Slope, Brooklyn, with writers for parents. Jonathan Baumbach was a novelist, and his mother, Georgia Brown, wrote diamond-cutting film reviews for the Village Voice. In 1986, they informed Noah and his younger brother that they were splitting. But what really happened then is irrelevant -- even though, after watching this, you'll wish you were in on those private conversations.

"Squid" represents Noah's poetic recall, as further spun into the gold of fiction; as redefined by the film's limited budget ($1.5 million) and shooting days (23 in all); and as interpreted by four staggeringly assured actors, particularly Jeff Daniels. This is analogue truth but what canny, desperate and enlightening truth it tells. "The Squid and the Whale" is an ache-to-the-touch, sometimes agonizingly funny, portrait of an American family.

When novelist Bernard (Daniels) and his wife, Joan (Laura Linney), also a writer, tell their children, 16-year-old Walt (Jesse Eisenberg) and 12-year-old Frank (Owen Kline), they're getting a divorce, the boys are shocked by the casual ease with which their parents drop the bomb. Bernard moves into a dilapidated, virtually empty house nearby and, before long, is sharing a roof with an attractive creative writing student (Anna Paquin). Joan starts dating Ivan (William Baldwin), Frank's eccentric tennis instructor.

Seeking easy explanation for the breakup, the boys assign blame. Walt, a slavish disciple of his intellectually boorish father, sides with Bernard, even before discovering that his mother had affairs during the marriage. Frank, very much his mother's son, champions Joan, despite the adultery, although this revelation has its consequences: Frank becomes obsessed with his mother's sexual past, starts drinking beer in private and masturbating in public.

Bad behavior isn't restricted to the children. Joan remains furious about Bernard's self-absorption, which she feels ruptured the marriage in the first place. She launches into the affair with Ivan with sanctimonious vigor, oblivious that it could upset the boys. Bernard, who is clearly threatened by Joan's growing success as a writer, treats her with thinly veiled aggression, and acts the part of the victimized, misunderstood cuckold.

No one's the villain in this movie, but Bernard certainly comes the closest. He dismisses "A Tale of Two Cities" as "minor Dickens." He refers to Franz Kakfa as "one of my predecessors." He's not just arrogant, he's thoughtless. When Walt asks him to inscribe something special inside the cover of his new book, Bernard reflects for a moment, then writes "Best Wishes" before scribbling in his autograph. Yet Bernard's desire to be venerated is also a wounded child's desperate search for affirmation. He also fears he's losing his talent -- if indeed he ever had it.

If there are mitigating circumstances to consider before judging Bernard, there's nothing ambiguous about his overbearing influence on Walt. His son parrots Bernard's opinions about books without even reading them. Kafka's "Metamorphosis," he loftily tells a prospective girlfriend, Sophie (Halley Feiffer), is "very Kafkaesque." (To which she bluntly replies: "It was written by Franz Kafka, so it would have to be.") Walt feels so artistically entitled, he performs a Pink Floyd song at a music competition and passes it off as his own. When confronted later about this, he replies his crime was a "technicality," since he "could have written it."

The movie's title refers to "The Clash of the Titans," a diorama at the American Museum of Natural History, which depicts those two sea creatures locked in eternal conflict. It's an image that Walt has retained from his childhood, after many visits with his mother to the museum. When he sees the titans in his own family as imperfect humans rather than monsters, he can evolve from the blind worship of his father to a more balanced view.

Baumbach, who directed 1995's "Kicking and Screaming" and co-wrote "The Life Aquatic With Steve Zissou," shows us that everyone in this family is too frustrated with and flummoxed by each other to see clearly.

Daniels, rumpled and shaggy as Bernard, is a jazzman in effortless control, swinging -- unpredictably -- from scurrilousness to vulnerability and back again. Linney exudes a mystical air of battered tenderness and deep secrets; you know there's more to her than the movie has time for. Eisenberg, so persuasive as the aspiring ladies' man in "Roger Dodger," is the empathetic center of the story, too simplistic for his own good but on the way to maturation. And Kline, the son of actors Kevin Kline and Phoebe Cates, is the movie's haunting canary, perfectly reflecting the family's emotionally stricken atmosphere. Collectively, they show that people should be judged by the text of their souls, not their hardback covers.

The Squid and the Whale (81 minutes, at area theaters) is rated R for strong sexual content and graphic profanity.

Anna Paquin with Jeff Daniels, above, and Jesse Eisenberg (kneeling) and Owen Kline in "The Squid and the Whale," the story of the effects of divorce on a Brooklyn family.