Singin’ in the Rain stars a popular silent film actor named Don Lockwood. He is partnered with Lina Lamont to whom he feels nothing special about despite the fact that the woman believes that they have a romantic connection.
During the premiere of his movie, The Royal Rascal, Don tries to evade his fans by hitching a ride with a woman named Kathy Selden, a stage actress who despises his career as a screen actor. Later that night, Don encounters Kathy again when she suddenly pops out from a mock cake. Don starts making fun of her. Kathy gets mad and she accidentally hits Lina with a cake she tries to throw it at Don. Kathy runs away but Dons desperately searches for her afterwards. Lina informs Don that she had Kathy fired. When Don finally gets ahold of Kathy, he learns that Kathy is an avid fan.
When their studio decides to release Don and Lina’s film as talking picture, their test screen is a disaster. The audience who are present laugh at Lina’s delivery of line which she speaks in a grating voice.
Don and his best friend Cosmo team up with Kathy in making their last film a musical. However, they main problem lies with Lina’s voice. To solve this problem, they decide to use Kathy’s voice in dubbing Lina’s. When Lina learns about this, she threatens to sue the studio if they decide to give credits to Kathy for her contributions in making the film. The head of the studio has no other choice but to leave Kathy out.
During the premiere of the film, fans are so enamored by the movie that they start requesting for Lina to sing live. When she lip syncs Kathy’s voice who is standing backstage, Don and his friends raises the curtains. Lina runs away and Don introduces Kathy to the audience. The movie ends with Don and Kathy starring in their new film, Singin’ in the Rain.