NOTE: This Spoiler was sent in by Boxset who says... "The Squid and the Whale is an excellent, bittersweet and unsentimental drama about the breakdown of a marriage and the problems of joint custody of two teenage boys."

The film is set in Brooklyn in 1986.  

Educated writers Bernard and Joan Berkman (Jeff Daniels and Laura Linney) live with their two teenage sons, Walt (Jesse Eisenberg), who is sixteen, and Frank (Owen Kline), who is twelve.   It becomes apparent that Bernard used to be successful, but that now he cannot get anything published, whereas Joan is beginning to make a name for herself as a writer.

When we first meet the family, they are playing tennis, and it is apparent that Bernard and Walt are both very competitive.

Later, over a family meal, Walt asks his father what he thinks of Hard Times.   He dismisses it as "minor Dickens" before arguing that schools teach all the wrong books, and that they'd be better off studying Great Expectations or David Copperfield.   Walt says he won't bother reading it, but Joan says he should and then make up his own mind about it.

Walt figures out how to play Pink Floyd's song Hey You on the guitar, and plays it for his parents, who are very impressed.   He says that he wrote the song and that he's going to enter it in a school talent contest.

Frank takes tennis lessons from Ivan, a former tennis pro and now coach, who could have been a big star if he hadn't suffered a knee injury early in his career.

One day while driving home, Bernard and Walt see Joan talking to a man from the neighbourhood.  

Bernard and Joan have a row one night, and the next day Bernard insists the two boys come straight home from school for a family conference.   That night, Bernard and Joan say that they are separating, but that they will share custody of both of them.  The boys will divide their week between the former family home, where Joan will stay, and Bernard's new house, which transpires to be a slightly dilapidated house a few subway stops away.

Walt tells Frank not to tell anyone about their parents' separation, but Frank has already told several people.   Walt blames his mother for the break-up and confronts her when Bernard lets slip that his wife had affairs, including one with the man they had seen her with on that earlier evening.  

Walt begins dating classmate Sophie (Halley Feiffer), a pretty but slightly plain girl.   In order to impress her, much of his talk is clearly copied directly from his father, in an effort to sound more intelligent than he actually is.  He refers to a book as "minor Fitzgerald" and recommends she read Metamorphosis by Franz Kafka, though he clearly hasn't read it himself.  Some time later, when Sophie starts a conversation about the book, he clumsily bluffs his way along, but lets his guard down when he refers to it as "Kafkaesque", which Sophie points out is obvious, given that it's written by Kafka.

Walt and Sophie indulge in heavy petting, but Walt wants to wait before they have sex.   He goes out for the evening with her family and it seems to be a success, but he has doubts about the relationship, especially when Bernard advises him to remain unattached and "play the field at his age".  One night, Walt and Sophie are thinking of going to a movie.  Walt asks his dad if he wants to go along.  They had planned on seeing Short Circuit, but Bernard suggests Blue Velvet.

Walt is also attracted to Lili (Anna Paquin), a student in Bernard's creative writing class, who writes provocative short stories.

When Lili risks being kicked out of her apartment, Bernard offers to put her up in the spare room of his house and she accepts.

Meanwhile, Frank is drinking regularly (there are plenty of cans of beer in his mother's house) and masturbating, smearing his emissions on school library books and lockers.  

Frank runs away from his father's house one night to stay at his mother's and discovers Ivan there.

Bernard and Lili begin an affair.   Walt enters the school talent show performing Hey You, and announcing it as a song he wrote. 

The concert is attended by their parents, with Ivan and Lili in tow, and Sophie.   Walt wins the contest, and prize money of one hundred dollars.  In the school lobby after the contest, Sophie is jealous when Lili asks Walt to come by her room later that night, saying that she wants to show him something.

Walt refuses to go along to a family meal after the concert, and insults his mother, who slaps him in the face.   Walking home, he has a row with Sophie, accusing her of pressurising him into having sex, and effectively splitting up with her.

That night, he is in Lili's room.   Lili explains how she knows that Hey You is really a Pink Floyd song, and says that she used to copy Lou Reed lyrics for poetry in creative writing classes.  She says she got caught out all the time, and that he'll be okay once it's not discovered that he didn't write the song.   Walt leans down and kisses her bare leg, but she moves her position on the bed and leans down over him, so that when raises his head again, he hits her in the face with the back of his head, causing her to have a nosebleed.   Lili says she's going to take a bath.  Walt shuffles back to his own room.

Lili and Walt attend a reading in a college that Bernard is giving.   The attendance is poor.  Bernard and Lili are called into the school after Frank's indecent acts are discovered.   They are subsequently called in again when it transpires that Walt didn't write Hey You.  He has to return the prize money and he is sent to an educational psychiatrist, who Walt is initially dismissive of, when he discovers that he only has a Masters Degree and not a Doctorate.

The psychiatrist asks Walt to talk about a happy memory.    He says himself and his mother once left a birthday party early so that they could go back home and watch Errol Flynn's The Adventures of Robin Hood on the television.   He also says that his mother used to take him to the Natural History Museum to see the exhibits, but that he was afraid of the squid and the whale, and would cover his eyes.  Later, when they'd get home, she'd describe it to him.  He still found it frightening, but not as much.

Walt returns home one night and finds his father in Lili's room, imploring her to give him oral sex. Walt flees the house and runs around the streets, ducking his head in the pond in Central Park before returning to his mother's house and admitting that he shouldn't have dumped Sophie.   Joan asks why he did, and he says he thought he could do better.

Bernard arrives to collect the boys but Frank refuses to leave.   Walt says he'll go back to his father's house, but when Frank is giving the cat to Walt at the front door, the cat runs out onto the street and under a parked car.   Bernard tries to retrieve the cat, but is further frustrated when a cop arrives to give him a parking ticket.  Bernard collapses in the middle of the street in what appears to be a heart attack, but which is later attributed to exhaustion.

At the hospital the next day, he tells Walt that Lili has left him and moved out.   Although Bernard argues that he'll need company now more than ever, Walt says he'd rather not stay at his place so much. 

Walt gets his father an extra pillow and goes into the corridor to tell a nurse that he wants to order some breakfast.

He runs out of the hospital and goes to the Natural History Museum to look at the exhibit of the squid and the whale.