Celie, a poor African-American girl, lives in rural Georgia in the early 1900s. She writes letters to God because her father Alphonso beats and rapes her. Due to the rape, she gives birth to two children, Olivia and Adam, whom Alphonso takes away. A farmer identified as "Mister" (Mr. __) asks to marry her younger sister Nettie, but Alphonso offers him Celie instead. Celie is abused by Mister and mistreated by his prior children. Nettie runs away and stays with Celie, but Mister eventually makes her leave after she refuses his unwanted sexual advances. Nettie promises to write, Celie never receives any letters, and Celie concludes that she is dead.
Mister's son Harpo marries an assertive girl named Sofia. Celie is impressed by Sofia's self-esteem, but Mister chides Harpo for what he considers weakness in his treatment of Sofia. In a moment of envy, Celie tells Harpo to beat Sofia. Sofia fights back and confronts Celie, who apologizes and confides in her about Mister's abuse.
Shug Avery, a jazz and blues singer and Mister's long-time mistress, moves in. Celie takes care of Shug, who is ill. While Shug is initially rude to Celie, the two become friends and Celie becomes infatuated with Shug. Frustrated by Harpo's domineering behavior, Sofia moves out, taking her children with her. Several months later, Harpo opens a juke joint where a fully recovered Shug performs nightly. Shug learns that Mister beats Celie, and vows to stay at the house until she is convinced he will stop. Shug and Celie grow closer and both women make love.
Shug tells Celie to go with her and they can be together as girlfriends and live freely. The day of Shug's departure arrives and Celie packs her bags and is about to leave with her but she is caught by Mister and Shug leaves while Celie suffers from the departure of her beloved and fears what awaits her now with Mister.
Sofia returns for a visit and gets into a fight with Harpo's new girlfriend, Squeak. She has a verbal spat with the mayor's wife, Miss Millie, and after the mayor slaps her, she hits him back. She is beaten by the police and sentenced to 12 years in prison. Squeak tricks the warden, her white uncle, into releasing Sofia from prison and having her work as Miss Millie's maid. The plan works, but the warden rapes Squeak. Sofia is released from prison and forced to work for Miss Millie, which she detests. Squeak cares for Sofia's children, and the two women become friends.
Shug returns to town, newly married to a man called Grady. Together, they learn that Mister has hidden letters from Nettie for years. In the letters, Nettie says she has befriended a missionary couple, Samuel and Corrine, and gone to Africa with them. Samuel and Corrine had unwittingly adopted Adam and Olivia. Through Samuel's story of the adoption, Nettie learns that Alphonso is her and Celie's stepfather. Their biological father was lynched, and their mother then suffered a mental collapse that Alphonso exploited. Nettie confesses to Samuel and Corrine that she is the children's biological aunt. Corrine, gravely ill, refuses to believe Nettie until Nettie reminds her that she had previously met Celie. Later, Corrine dies, having accepted Nettie's story.
Celie visits Alphonso, who confirms Nettie's story. Celie confides to Shug that she is losing faith in God; Shug explains to Celie her own unique religious philosophy. Celie, Shug, and Squeak decide to leave town; Celie curses Mister before leaving him. They settle in Memphis, Tennessee; Celie starts a pants-making business.
Alphonso dies. Celie inherits land that rightfully should have been passed down to her and Nettie because it belonged to her biological father and mother. She moves back into her childhood home. Celie is crushed when Shug falls in love with Germaine, a member of her band. Shug travels with Germaine, writing postcards to Celie. Celie pledges to love Shug even if Shug does not love her back. Celie learns that Mister is suffering from a considerable decline in fortunes, and begins calling him by his first name, Albert. Mister proposes that they marry "in the spirit as well as in the flesh", but Celie declines.
Nettie and Samuel marry and prepare to return to America. Before they leave, Adam marries Tashi, an African girl. Following tradition, Tashi undergoes female genital mutilation and facial scarring. In solidarity, Adam undergoes the same facial scarring ritual.
As Celie realizes that she is content without Shug, Shug returns, having ended her relationship with Germaine. Nettie, Samuel, Olivia, Adam, and Tashi arrive at Celie's house. Nettie and Celie reunite after 30 years, introducing one another to their respective families.
