Tracy Chambers is a beautiful African American designer who just debuted her fashion show in Rome, Italy. As she receives the audience’s applause, she remembers her days as a poor student in the slums of Chicago, Illinois. One night, as Tracy walks home, she passes Brian Walker, a community activist, using a bullhorn to garner support to halt the demolition of his neighborhood. He attempts to get Tracy’s attention, but she lambastes him for making so much noise when people are trying to sleep. The following day, Tracy watches Brian address a crowd as another apartment house is demolished. While he rants against wealthy landlords destroying their neighborhood, he is heckled by a group white of construction workers, who yell that they are fumigating the “dump.” As Brian moves his van so a garbage truck can get by, Tracy pours milk into his bullhorn. When Brian picks up the megaphone, milk sprays onto in his face. The young activist attacks the construction workers and soon white laborers are battling black residents as Tracy laughs and waives her milk carton. The next morning, Tracy bails Brian out with a bad check. He offers to repay to her by bringing the cash to her place, but Tracey tells him to get the money all in nickels so he can slide them in her mail slot. Tracy then rushes to her job as a secretary for Miss Evans, the head of the display department at an upscale department store. Evans warns Tracy that she will have to give up her fashion studies if she continues to be late. They walk to the storage area where Sean McEvoy, a glamour photographer, shoots models for a telescope advertisement. Sean mistakes Tracy for a model, but Evans corrects him before sending Tracy for coffee. Later, Tracy is home sewing when hundreds of nickels pour through her mail slot. Opening the door, she finds Brian, who invites her to lunch. During their date, Brian explains that he got into activism to stand up for the "little guy," white or black, against the greedy elite. Tracy declares that she wants to be a famous designer and get out of the ghetto. The next day, Sean photographs Tracy wearing a dress she designed. Sean is impressed and tells her she should come with him to Rome. Mrs. Evans arrives and informs Sean that the store refuses to use black models in its advertising. Later, Tracy assists Sean as he shoots a fashion layout with models and street people in front of a derelict tenement building. Brian arrives and is offended by Sean’s exploiting his people and when Tracy defends Sean's artistic vision, Brian tells her goodbye. Later, Sean insists Tracy will be hearing from him, kisses her, and leaves. A few days later, Tracy is fired when Mrs. Evans discovers she took a sick day to show her designs to clothes manufacturers. Tracy goes to the unemployment office where she runs into Brian campaigning for city alderman. She takes Brian home and they make love. Soon, Tracy is managing Brian’s campaign. One night, he asks her to skip her studies to meet a congressman. When she protests, Brian disparages her dreams, telling her to deal with the reality of the ghetto. At home, Tracy receives a telephone call from Sean asking her to do modeling work in Italy. In Rome, Sean renames Tracy “Mahogany” and arranges an audition with Garina, the top modeling agency in Europe. The audition is held in a bare room with ten men and a woman, who negatively criticizes her legs and breasts. Tracy erupts, telling them they want a mannequin and asks why they do not hire the sole woman of the group. The woman, Carlotta Garina, explains she is too busy running the agency to model and hires Tracy. Soon Tracy is the biggest model in the world, appearing on magazine covers and billboards. One day, Sean invites her to his apartment to make love to her, but is impotent. Tracy tells him he does not have to prove his masculinity with her, implying he is a homosexual. The next day, Tracy demands to wear one of her designs at a photo shoot, but Sean rips her top off, telling her to wear the clothes she was given. That night, at a charity fashion auction, Tracy appears wearing one of her creations instead of the gown she was given. The crowd bursts into laughter when Sean bids a mere five hundred lire for it. As Tracy fights back tears, Christian Rosetti, an elegantly dressed Italian, bids 2 million lire. After the show, Tracy is introduced to Christian, but Sean interrupts them, demanding to speak to her. After refusing Sean’s apologies, Tracy goes back to her apartment and hears nickels dropping outside her room. She opens the door and finds Brian. The next morning, Brian explains that he lost the election, but has gathered enough support to run for congress and asks for her help. That night, Tracy and Brian go to a party Sean is throwing in her honor. Seeing that Brian is uncomfortable with the homosexuals and transvestites in attendance, Sean invites him to view his weapon collection. Upstairs, Sean pulls out a pistol, cocks it and points it at Brian. Brian leaps on the photographer and forces him to the ground, sticks the gun in his mouth and pulls the trigger. Sean laughs that the gun is not loaded. Brian finds Tracy, tells her he cannot live this life and storms out of the party leaving Tracy screaming, “Do you know who I am?” As images of her are projected on a wall, Tracy disrobes and drips melted candle wax on herself while the partygoers cheer. Hours later, a drunken Tracy returns to her apartment to find Brian packed and ready to go. She screams that Brian hates her because she is a winner and he is a loser, but he warns her that no matter how successful she becomes, she will be unhappy if she has no one she loves to share it with. The next day, Tracy is shooting a commercial when she accidentally bumps a camera truck with the sports car she is driving. Sean pushes her into the passenger’s seat, gets behind the wheel and speeds down the highway. He releases the steering wheel, accuses Tracy of leaving him for Brian and snaps pictures of Tracy screaming in horror. Tracy turns off the ignition, which locks the steering wheel, and causes them to crash. Sean is killed. After weeks of convalescing at his villa, Christian gives Tracy a garment factory to start her own line of clothing. He explains they are partners and the business will be a success if both partners get what they want. Months pass and Tracy is completely healed. As the deadline approaches for her debut show, she becomes abusive to her staff, threatening to fire them for the smallest mistake. Christian informs her the workers are unhappy, but she screams she is not paying them to be happy. A month later, Tracy shows her designs, based on kabuki theater, to the world. As the audience applauds, she hears Brian’s voice in her head saying that success means nothing without someone you love to share it with. Tracy leaves the stage and asks Christian to take her home. There, Christian tells Tracy it is time she repaid him for his generosity and tells her to go into his bedroom. Although Tracy is willing to keep her end of the bargain, her lack of enthusiasm changes Christian’s mind. Instead, he arranges for Tracy to return to the United States. In Chicago, Tracy arrives at one of Brian’s campaign speeches and heckles him from the crowd. When he sees her, he leaves the stage and they embrace.