In 1909, Celie is an African-American girl in rural Georgia who has had two children by her abusive father, both of whom have been taken from her. Her father then gives her away as a wife to widower Albert “Mister” Johnson, who already has three children and who also abuses Celie and the children treat her badly. Celie’s younger sister, Nettie, the only person who loves her, runs away from home when their father starts abusing her and seeks shelter at Celie and Mister’s home. The sisters promise to write each other should they ever be separated. Nettie teaches Celie to read and the two are happy together until Mister tries to rape Nettie while on her way to school. She successfully fights him off and is forcibly removed by him from the property.
Seven years later, Celie is now a meek adult who has avoided standing up to Mister’s continued abuse. His eldest son, Harpo, marries his pregnant girlfriend, Sofia, a strong-willed, boisterous woman, and Celie is shocked to find her running a matriarchal household. On Mister’s advice, Harpo attempts to overpower and strike Sofia in an attempt to better control her. After he fails, he asks Celie what to do. Confronted with her own inability to stand up to abuse, she also advises Harpo to start beating Sofia. Sofia forcefully retaliates and confronts Celie about what she told Harpo. She also reveals she has had to fight off abuse from all the men in her family. She threatens to kill Harpo if he beats her again and tells Celie to do likewise to Mister. After Harpo doesn’t change his ways, Sofia leaves him, taking their children with her.
Mister and Harpo bring home Shug Avery, a showgirl and the former’s long-time mistress, as she suffers from an unknown illness. Celie, who has slowly developed a fondness for Shug through a photograph sent to Mister, is in awe of Shug’s strong will and ability to stand up to Mister. She nurses Shug back to health over the next six years, and Shug in turn takes a liking to her, writing and performing a song about her at Harpo’s newly opened bar. That night, Shug tells Celie she’s moving to Memphis, and Celie confesses to Shug that Mister beats her when Shug isn’t there for not being her. Shug tells Celie she’s beautiful and that she loves her, and the two women kiss. Celie decides to follow Shug to Memphis, but gets caught by Mister while she’s frantically packing her things.
Meanwhile, Sofia has been imprisoned for striking the town’s mayor after he assaults her. Years pass, and she, now a shell of her former self, is released from prison – only to be immediately ordered by the judge to become a maid to the mayor’s wife, Ms. Millie. Having not seen her children in eight years, Sofia is allotted Christmas to be with her family. As Ms. Millie tries to drive home, she panics after encountering a group of Sofia’s friends trying to help her, ordering Sofia to help her drive home before Sofia can spend any time with her children.
Shug returns to Celie and Mister’s home with her new husband, Grady, expecting to receive a recording contract. Shug gives Celie a letter from Nettie, who tells her that she’s working for a couple that has adopted Celie’s children. Celie and Shug realize that Mister has been hiding Nettie’s letters from Celie; while he and Grady are out drinking, the two search the house and find a hidden compartment under the floor boards filled with dozens and dozens of Nettie’s letters. Engrossed in reading, Celie does not hear Mister’s calls to shave him and he beats her. Celie attempts to kill Mister with a straight razor, but Shug intervenes and stops her. At a family gathering, Celie finally speaks up against Mister to the delight of Shug and Sofia, who finds her old fighting spirit, which prompts Harpo’s new wife, Squeak, to stand up for herself as well. Shug and Grady drive away, taking Celie and Squeak with them.
Years later, Celie owns and operates a tailor shop. Mister is old, a drunk, and alone, and Harpo has made amends with Sofia; the two now run the bar together, and Shug still performs there. Celie’s father passes away, and she finally learns from Nettie’s letters that he wasn’t their biological father and that when their mother passed, “his” property was legally inherited by Celie and Nettie. Mister receives a letter from Nettie addressed to Celie, takes money from his secret stash, and arranges for Nettie, her husband, and Celie’s children to return to the U.S., where they finally reunite while Mister watches from a distance.