Singin' in the Rain is set in 1927. The silent movie era's greatest stars Don Lockwood and Lina Lamont greet their adoring public after the triumphant premiere of "The Royal Rascal". Whilst walking to the show party, Don stumbles into Kathy Selden who appears to be the only woman in the world who hasn't heard of him (though it later turns out this is a ruse).

At the party RF Simpson, the owner of Monumental Pictures gives a demonstration of a new idea, Talking Pictures. This is dismissed by all present as a gimmick that will never last. At the same party Kathy is revealed as a showgirl, when she bursts out of a cake. Annoyed at Don's taunts she launches a cream cake at him, but he ducks and it hits Lina.

During filming Lina boasts that she has had Kathy fired much to Don's disgust. Disaster strikes the studio when the first talking picture is a huge success. RF stops the filming and insists that his film must also be a talkie. There is just one problem; though Lina is beautiful, her voice sounds like a strangled cat.

Both Don and Lina have tuition in speach but Lina does not improve - it seems that "The Duelling Cavalier" is doomed to failure. Then Cosmo, Don's best friend has the brilliant idea of changing it into a musical and dubbing Lina's voice with Kathy's.

The premiere is a huge hit and Lina declares that she has a contract which means Kathy will have to go on singing and talking in Lina's films, thus ending Kathy's hopes of stardom in her own right. Lina insists on addressing her adoring fans at the premiere, but when they insist she sing for them she is forced to rely on Kath standing behind the curtain covering for her. Don, RF and Cosmo have other ideas however............