Columbia graduate and ex-Olympic medal winner Leo Percepied is a published writer, but is forced to live with his mother Charlotte in a small San Francisco apartment to make ends meet. Despite critical acclaim for his first novel, Leo has not received the meager $500 advance from his publisher. His mother insinuates that at 28 years of age, Leo should settle down with a job and "a real nice girl," but Leo seeks an adventurous life on which to base his books. One day, his mother's nagging drives Leo to seek the underground beatnik nightlife in the North Beach area, where a crowd of bohemians tease and cajole him into joining them at a coffeehouse. As he enters, Leo witnesses a quarreling couple, Mardou Fox and Julien Alexander end their relationship with a shouting match of poetic rebuttals. Seeing Leo's immediate attraction to Mardou, kindly Yuri Gligoric warns the newcomer that Mardou is mentally unstable. When the group moves to another club, a spotlight shines on patrons who introduce themselves. Dancer and painter Roxanne, who masks herself in white face paint with kohl encircling her eyes, claims she is in love with herself, while successful novelist Arial Lavalerra tells the crowd he sells his dreams to Hollywood. When the light falls on Mardou, she explains that she is from a war-torn French village, where the invading army took her mother, a prostitute, away. When she asks whom to love, Leo comes to Mardou's side and offers his services. Later the group drops by the mission, where Reverend Joshua Hoskins and his wife are feeding dozens of painters and poets. When the brooding Mardou flippantly asks Joshua how much spaghetti it takes to save a soul, he sagely asks how much bitterness it takes to destroy one. By early morning, Mardou takes Leo back to her apartment where they dance and embrace in desperate need for each other's love. When they awake later in the morning, a bitter Mardou admits that she sees an analyst and lives on an allowance from the mental health clinic. When she dismisses her love for Leo as temporary, he offers to give her whatever she needs and drives her to her analyst appointment. Mardou tells her analyst that despite jumping from one relationship to another out of loneliness, she hopes to one day believe someone's promises. Later, Leo suggests that once he receives his advance they might start a life together in Mexico. Mardou then visits Roxanne, who cautions that "writers watch themselves live," and Leo will finish with his affair when he finishes his book, but Mardou dismisses the self-hating Roxanne. When Leo meets Mardou at a bar with his all his belongings, she invites him to live with her, but soon after, Leo tells Mardou that his obsession with her is preventing him from writing in such close quarters. Frantic that her trust is not being returned, she suggests that he give up writing for her. When he insists that his writing comes first, she throws his papers across the room in a tantrum. Later at a party, Leo, believing that Mardou is the cause of his writer's block, turns his attention to Roxanne, who is romancing the crowd with an impromptu dance solo. Leo attempts to join her, but Roxanne flees the room in tears. When Leo finds her in a bookstore, Roxanne tells him she hates men, causing Leo to kiss her passionately. Yuri visits Mardou at her apartment and sees that Leo's accusations that she caused his writer's block have nearly destroyed her love for Leo. After making love to Roxanne, Leo returns to Mardou’s apartment drunk and professes his guilt, but Mardou cannot forgive him and taunts him about returning to his mother. Leo berates her for being frigid and suggests that she engage in life and "go naked in the world." After he passes out, a distraught Mardou undresses and runs through the streets nude. When the police chase her, she runs to the safety of the mission. The next morning, Leo wakes to find Yuri, who witnessed the argument and now asks if he can date Mardou. Leo insists that he will marry Mardou, but Yuri mocks his wedding idea. Meanwhile, Mardou tells her analyst that she is pregnant and her analyst suggests an abortion. When Mardou retorts that nothing would make her kill the love that grows inside her, the analyst is gladdened by Mardou's recognition of love. After days of searching for Mardou, a drunken Leo calls Charlotte, who tells him the advance has arrived and begs him to come home. Leo announces that he is getting married as soon as he can find the girl. Later at a club, Roxanne tells Leo she hates him for using her, but she now understands love and loneliness and is leaving the underground to find a more settled life. Meanwhile, Mardou returns to her apartment to find Yuri, who professes his love for her. Although Mardou feigns indifference about Leo, she insists on finding him so she can taunt him. When they find the disheveled and drunken Leo, Yuri tries to tell him that Mardou still loves him, but Mardou viciously attacks Leo, coyly claims to love everyone and throws Julien's knife at him, nearly hitting him. Yuri tells Leo that she was throwing the same pain Leo threw at her last night. Later, Mardou invites dozens of bohemians to a party at her apartment where Leo grabs Mardou in frustration. Mardou screams that she is pregnant with his child and demands to have a man who can be a father, not a child. When Mardou then breaks down and admits her love for him, Leo professes his love and promises to grow up before the child does. As the bohemian crowd makes their way to another North Beach party, Leo and Mardou embrace their future together.