Drossmouth, like many provincial towns across the country, boasts its own prolific and accomplished repertory theatre company. Performing new plays on a weekly basis, the company work to a strict principle: the show must go on, Monday next.

At the first rehearsal of their next play, 'Tarnished Gold', the company's producer, Harry Blacker, announces the expected arrival of its author, an unknown called Jeremy St Clair. Harry is already anticipating conflict with someone he expects to be a cantankerous amateur, but is surprised when the playwright arrives in the guise of elderly spinster Catherine Beckworth. He quickly realises that Catherine is the aunt of theatre director Roderick Beckworth, explaining why the executive insisted on staging the play.

With tempers already fraying, young starlet Avis causes further interruption with an emotional outburst brought on by a letter instructing her to return home. Harry is reminded that he agreed to fire Avis because she is a terrible actress, but he ignores the outburst and rehearsals finally begin. The play's weaknesses immediately become clear, so Harry sends Catherine away to rewrite the first act.

Meanwhile, the company's leading man, Norwood Bellamy, arrives at the theatre having received a lift from admirer Sarah Stebbins, an older woman he is flirting with. His wife, Sandra Bellamy, arrives separately but, seeing her husband with Sarah, confronts him about his flirting. The argument is interrupted by a telephone call from Stella Film Productions, which Norwood is eager to take.

Rehearsals continue and Harry becomes more anguished as the dreadful dialogue in 'Tarnished Gold' deteriorates even further. Catherine returns with renewed optimism for her updated first act, but Harry casually throws it away. Furious at his insolence, Catherine phones her nephew to complain and intercepts the call from Stella Film Productions, much to Norwood's annoyance.

The company break for lunch and Maude, the matriarch of the company, persuades Avis to go home and give up her dreams of stardom. She gently advises her that she was never going to have a stage career and reveals that she herself had given up her chance of fame for marriage and, because she was eventually betrayed, now struggles financially. Recognising the difficulties faced by Maude in spite of her greater talent, Avis accepts that she will never be a star and says she will return to her father.

Norwood is disappointed at losing the call from the film company and angrily humiliates Sandra when she points out that the message for 'Bellamy' could be for her. He mocks her for thinking Stella Film Productions would be interested, but they call again asking specifically for Sandra. Mr Stebbings, Sarah's angry husband, suddenly arrives and assaults Norwood. Sandra initially laughs at Norwood's shame but, after seeing his embarrassment, she begins to reassure him. In return, he encourages Sandra to take the unique film offer and confirms that he will go to London with her. Reunited, Sandra quickly dismisses Sarah, who has returned to ask about Norwood's well being.

Avis finds herself alone with Jerry, a young actor who is falling for her. He tries for a kiss, just as her father arrives. He tells Avis that her letter was from her aunt, who, he adds, had no business writing it. Catherine knows Avis's father as he's the vicar from her parish, and she talks him into taking his daughter home.

As the company return from lunch, Harry trips and falls into the orchestra pit. Catherine takes charge and moves him into a dressing room, encouraging the company to continue rehearsing while they wait for a doctor. Appalled at the idea, the company initially resist, but Sandra takes pity on Catherine and talks everyone into letting her direct. During the dire rehearsal - attempting to follow the Meyerhold system of directing according to a huge stage grid - Harry appears ghost-like at the back of the theatre and accidentally knocks Catherine out with a stage weight.

A week later and the first night is a success. As the company take their final bow, the audience praise the author. Harry happily beckons Catherine to take her applause.