NOTE: This spoiler was submitted by Jeremy
The film opens at the First Avenue nightclub where the band The Revolution is playing their song "Let's Go Crazy". The lead singer, The Kid (Prince) has an energetic style that the people seem to dig. Arriving at the nightclub is aspiring performer Apollonia (Apollonia Kotero), who wants to see the manager. He's not there, so one of the ladies that works there takes down Apollonia's information. After The Revolution is done playing, Morris Day and The Time begin to play, the former having a rivalry with The Kid.
The Kid lives at home with his mother (Olga Karlatos) and his father (Clarence Willliams III). The father physically abuses the mother, and strikes back at The Kid whenever he tries to defend her.
Morris and the club's owner Billy (Billy Sparks) discuss getting a new group to replace The Revolution since people are getting tired of The Kid's schtick. Morris wants to organize an all-girl group, and Billy appears to be on board.
The Kid pursues Apollonia. He takes her for a ride on his motorcycle and rides to a lake, where he tells her he will help her break out if she gets into the water of Lake Minnetonka. Apollonia strips down to her underwear and jumps into the water. The Kid then says that it's not Lake Minnetonka. He gets on his motorcycle and begins to ride away, leaving Apollonia naked and pissed. However, he stays and lets her climb back on.
Two members of The Revolution, Wendy (Wendy Melvoin) and Lisa (Lisa Coleman), frequently write music for the band and ask The Kid to give it a listen, but he never does and he continues to refuse to use their music, which causes tension between the band. The Kid mocks their sentiments using a puppet.
Morris approaches Apollonia to join the girl group. He buys some fancy champagne and tries to convince her that The Kid can't help her kickstart her career since he can hardly get his own career off the ground. As The Kid performs, he watches the two of them sitting together. With The Revolution, he sings "The Beautiful Ones," which brings Apollonia to tears.
After the show, The Kid brings Apollonia to his home. He plays a track in his room that sounds like a woman moaning erotically, but he tells Apollonia that the woman is crying, and he is just playing the track backwards. The Kid then passionately kisses Apollonia and they make love for the first time.
Morris eventually persuades Apollonia into joining the group. She goes to The Kid's home and gives him the news. He reacts by angrily slapping her the way his father does to his mother.
The Kid learns from Billy that he plans to cut one of the acts for the club. This leads The Kid to go on a motorcycle ride to have time with his thoughts (while "When Doves Cry" plays). This is cut between moments he shares with Apollonia. When he returns home, he finds his mother on the front steps crying. He enters his home to confront his father. The Kid finds him in the basement smoking a cigarette and playing the piano. He learns that his father has composed several musical pieces of his own, but he claims to have not written them down. When he asks his son if he has a girlfriend, The Kid says yes, and his father tells him not to get married.
The Revolution performs "Computer Blue", with The Kid acting out like he's getting a blowjob on stage. The audience doesn't appear to be digging his music. Apollonia and Morris show up. The band starts playing the very provocative "Darling Nikki", which makes Apollonia uncomfortable and humiliated. After she leaves, The Kid goes into his dressing room and starts taking out his anger. Billy enters and criticizes him, comparing him to his father and his own failed musical career.
Soon, the girl group, Apollonia 6, make their debut at the club. Their song, "Sex Shooter", is a hit, and Billy continues to hint at The Kid that they'll be taking his spot. After the show, Apollonia and Morris (who is drunk) are walking together. The Kid comes to get her on his motorcycle once Morris starts to get fresh. They ride by a bridge, where The Kid starts getting aggressive with Apollonia. She leaves him.
When The Kid returns home, he sees that the place is a mess, and his mother is gone. He goes down to the basement, and his father shoots himself in the head with a handgun. The medics take him away. The Kid starts raging out in the basement, whereupon he discovers his father's compositions. The following morning, he picks up a tape of a song that Wendy and Lisa wrote, "Slow Groove". It inspires him to start composing.
That night, The Time plays their set to a satisfied crowd. After the performance, Morris goes by The Revolution's dressing room and tauntingly asks The Kid, "How's the family?" His buddies laugh, but Morris quickly regrets what he said.
The Revolution goes up to play. Before the song, The Kid announces that they're playing a song written by Wendy and Lisa, which he dedicates to his father. The song is "Purple Rain". It thrills the crowd so much that even Billy sheds a tear. Once the song ends, The Kid goes backstage and plans to hop on his motorcycle, but he hears the enthusiastic cheering and goes back, where the other musicians congratulate him and cheer him on. He sees Apollonia as well, who appears to have forgiven him. He returns to the stage and plays "I Would Die 4 U". This is cut between scenes of him visiting his father at the hospital with his mother, as well as Apollonia visiting The Kid in the basement.
The film concludes with a shot of The Kid giving the audience one more intense look.