An acting company prepares to rehearse the play Mixing it Up by Luigi Pirandello. As the rehearsal is about to begin, they are unexpectedly interrupted by the arrival of six strange people. The Director of the play, furious at the interruption, demands an explanation. The Father explains that they are unfinished characters in search of an author to finish their story. The Director initially believes them to be mad, but as they begin to argue among themselves and reveal details of their story, he begins to listen. The Father and The Mother had one child together (The Son), but they have separated and Mother has had three children by another man – The Stepdaughter, The Boy and The Child (a girl). The Father attempted to buy sex from The Stepdaughter, claiming he did not recognize her after so many years, but The Stepdaughter is convinced he knew who she was the entire time. The Mother walked in on The Father and The Stepdaughter shortly after The Father's proposal and informs The Stepdaughter that he is her ex-husband; they both express their disgust and outrage. While The Director is not an author, he agrees to stage their story despite disbelief among the jeering actors.
After a 20-minute break, The Characters and The Company return to the stage to perform some of the story so far. They begin to perform the scene between The Stepdaughter and The Father in Madame Pace's shop, which the Director decides to call Scene I. The Characters are very particular about the setting, wanting everything to be as realistic as possible. The Director asks The Actors to observe the scene because he intends for them to perform it later. This sparks the first argument between The Director and The Characters over the acting of the play because The Characters had assumed that they would be performing it, seeing as they are The Characters already. The Director continues the play, but The Stepdaughter has more problems with the accuracy of the setting, saying she doesn't recognize the scene. Just as The Director is about to begin the scene once more, he realizes that Madame Pace is not with them. The Actors watch in disbelief as The Father lures her to the stage by hanging their coats and hats on racks, and Madame Pace follows, "attracted by the very articles of her trade".
The scene begins between Madame Pace and The Stepdaughter, with Madame Pace exhorting The Stepdaughter, telling her she must work as a prostitute to save The Mother's job. The Mother protests at having to watch the scene, but she is restrained. After The Father and The Stepdaughter act half of the scene, The Director stops them so that The Actors may perform what they have just done. The Characters break into laughter as The Actors try to imitate them. The Actors continue but The Stepdaughter cannot contain her laughter as The Actors use the wrong tones of voice and gestures. The Father begins another argument with The Director over the realism of The Actors compared to The Characters themselves. The Director allows The Characters to perform the rest of the scene and decides to have the rehearsals later.
This time, The Stepdaughter explains the rest of the scene during an argument with The Director over the truth on stage. The scene culminates in an embrace between The Father and The Stepdaughter, which is realistically interrupted by the distressed Mother. The line between reality and acting is blurred as the scene closes with The Director pleased with the first act.
The final act of the play begins in the garden. It is revealed that there was much arguing among the family members as The Father sent for The Mother, The Stepdaughter, The Child, The Boy, and The Son to come back and stay with him. The Son reveals that he hates the family for sending him away and does not consider The Stepdaughter or the others a part of his family. The scene ends with The Child drowning in a fountain, The Boy committing suicide with a revolver, and The Stepdaughter running out of the theater, leaving The Son, The Mother, and The Father on stage. The play ends with The Director confused over whether it was real or not, concluding that in either case he lost a whole day over it.