In the late 1920s, at Portsmouth’s modest Theatre Royal, Polly Browne [Twiggy] steps into the spotlight as understudy when the show’s star, Rita Monroe [Glenda Jackson], is sidelined by a broken ankle. The company is pulling together a Saturday matinée of The Boy Friend, with the charming but distant Tony Brockhurst [Christopher Gable] as the male lead and the once American child dancer Tommy [Tommy Tune] keeping spirits high. Polly, who knows the show by heart, becomes indispensable, and the prospect of a new chapter in her life begins to unfold as the rehearsal tempo quickens and the backstage hum grows louder.
Into this already tense atmosphere arrives Mr. De Thrill [Vladek Sheybal], a Hollywood talkie director weighing a possible film adaptation. His presence sharpens Max Mandeville’s nerves, and the director’s anxieties ripple through the company as they improvise to accommodate the new possibility. Ambition crackles in the wings, especially with Maisie [Antonia Ellis], a chorus girl eager to use any opportunity to climb higher, while the others sense the looming pressure of a potential big-screen version.
As the first act unfolds, Polly receives quiet encouragement from Rita Monroe’s backstage visits and from the rest of the cast who sense her nervous resolve. On stage, the Polly Browne and Tony partnership blooms into a light, comic romance within the musical, even as real-life attraction starts to mirror their onstage flirtation. Polly’s heart grows warmer during intermission when she sings to a picture of Tony, a moment glimpsed by De Thrill, while Maisie works to steer the director’s attention away from the scene. When Polly spots Tony seemingly flirting with chorus girl Dulcie [Caryl Little], doubt gnaws at her, and misgivings begin to color the backstage atmosphere.
In the second and third acts, Polly’s mood darkens with suspicion, while the men in the company—led by Tommy—take playful revenge on Maisie for her scheming by sabotaging their joint number. De Thrill’s fascination with Polly intensifies the backstage melodrama, and the illusion of the musical romance blurs with the real-life affair that threatens to derail the show. The tension peaks as Polly confronts Tony’s supposed flirtation with another dancer, and the ensemble’s farcical attempts to impress the Hollywood guest grow more chaotic. Yet on the night’s finale, the two lovers find a genuine moment of solace: Tony comforts Polly on stage as her Pierrette costume frames a poignant image of their shared longing.
In an unscripted flourish, Tony and Dulcie deliver a cake to Polly, and Tony proclaims his love in a spontaneous, heartfelt moment that ties together the musical’s fantasy with the real feelings brewing behind the curtain. The moment brings a quiet, satisfying close to both storylines: the backstage world acknowledges Polly’s growth, and the audience—especially Rita Monroe, moved to tears by the performance—recognizes that Polly has proven herself. De Thrill, however, makes a final choice about his plans: he decides not to adapt The Boy Friend, but leaves Polly a card inviting her to Hollywood.
Maisie, certain she will be the director’s choice, is surprised when De Thrill turns his attention to Tommy—revealing him as his long-lost son—and departs with him instead. Left with the card but little else, Polly chooses to stay in London with Tony, embracing a future defined by love, loyalty, and a life spent on the stage rather than the bright lights of Hollywood.