Zorg is a thirtysomething aspiring writer making a living as a handyman for a community of beach houses in the seaside resort at Gruissan on France's mediterranean coast. He meets 19-year-old Betty, a volatile and impulsive young woman, and the two begin a passionate affair, living in his borrowed shack on the beach. After a row with him where she tears apart and smashes up the house, she finds the manuscript of his first novel, reads it in one long sitting and decides he is a genius. However, after another argument with his boss, she empties the shack and burns it down. The two decamp to the outskirts of Paris, where her friend Lisa has a small hotel. Betty laboriously types out Zorg's novel and submits it to various publishers. They meet Lisa's new boyfriend Eddy, and the four have many fun times, often fuelled by alcohol. They find work in Eddy's pizzeria but a fight erupts in which Betty stabs a customer with a fork. Zorg tries to slap her back to her senses. Though Zorg hides the rejection letters Betty finds one and, going to the publisher's house, slashes his face. Zorg induces him to drop charges by threatening him with violence, saying she is the only good thing in his life and she is all he has. Eddy's mother dies and the friends go to the funeral in Marvejols. There, Eddy asks Zorg and Betty if they will live in the dead woman's house and look after her piano shop. Zorg enjoys the quiet provincial life and makes friends with the grocer Bob, his sex-starved wife Annie and various offbeat characters, but Betty's violent mood swings are a concern. One day, after an irritating comment from Zorg, she punches out a window with her bare hand and goes on a screaming flight through the town. Happiness seems on the horizon when a home test suggests Betty is pregnant, but a lab test is negative and she sinks into depression and tells him she is hearing voices talking to her in her head. Zorg, masquerading as a woman, robs an armoured cash collection van delivery headquarters, holding the guards at gunpoint and tying them up. He attempts to use the money to buy Betty's happiness, but she fails to respond and enacts yet another prosecutable offence by luring a small boy away from his mother and taking him to a toy store. Zorg finds her and they both flee from the authorities as they rush to rescue the boy. One day Zorg comes home to find blood all over the place and Betty gone. Bob tells him she has gouged out an eye and is in the hospital. Rushing there, Zorg finds her under heavy sedation and is told to come back the next day. Going home, he receives a phone call from a publisher accepting his manuscript. On his next visit to the hospital, he finds Betty restrained and catatonic. He becomes agitated and a doctor tells him she will need prolonged treatment and may never recover her sanity. Zorg reacts by blaming her illness on the medication being administered and physically attacks the doctor. He is forcefully ejected from the hospital after a violent struggle with three orderlies. Returning in disguise, he whispers his farewells and smothers Betty with a pillow. Going home, he sits down to continue his current book.
