Don Lockwood (Gene Kelly) and Lina Lamont (Jean Hagen) are a hot couple in silent films. However, when the change to talkies happens, Lina's voice is much too strident to use. Don Lockwood's best friend, Cosmo (Donald O'Connor), devises a plan to dub someone else's voice into Lina's scenes. Kathy Selden (Debbie Reynolds) is hired to be Lina's voice. Don Lockwood falls in love with Kathy which spikes major jealousy in Lina. She demands that Kathy be given no credits for doing her voice, and the studio has to bow to her demands, because the movie has already been partially shot. At the movie premiere, the audience wants Lina to sing a song live. Lina is frantic knowing what would happen if she really tried to sing, so once again she demands that Kathy sing for her from behind a curtain. The increasingly-bitter Kathy doesn't want to but is convinced to do it. While the two women are singing the number, the men open the curtain to reveal what's really going on to the audience.