Ellie Clayton and Angela Simms give superb performances in the new stage adaptation of Letter to Brezhnev, now playing at the Royal Court, Liverpool. The production is a funny, tender version that hugs close to the 1985 film.

By some quirk of marketing, Letter to Brezhnev has always been associated with Margi Clarke. In the 1985 movie, she played Teresa, the sharp-talking chicken-factory worker out for a good time in post-industrial Liverpool. Yet the film, as the Guardian's review argues, rightly belongs to Alexandra Pigg as Elaine, Teresa's best friend, who trades a dead-end life of unemployment for a fantasy fling with a Russian sailor.

A few years before the collapse of the Soviet Union – and a year before Willy Russell's similarly themed Shirley Valentine – Elaine dared to believe in escape and in border-defying love. The character remains as winning on stage as on screen. Clayton plays her with much the same combination of wit and wonder that Pigg brought to the role.

Elaine is a Kirkby girl who has a night on the town with a wallet of stolen cash and finds the world unexpectedly opening up to her. She can be naive, petulant and cynical. She never lets the audience stop rooting for her.

The adaptation's return to Liverpool, the city that produced the original film, gives the Royal Court production a particular charge. For a story about Merseysiders and Russian sailors, staged in the heart of the city where it was set, the resonance is built in.

Clayton and Simms lead a production that balances comedy with tenderness, staying faithful to a film that captured a specific moment: post-industrial Liverpool, Cold War Europe and a young woman's stubborn refusal to accept that her life had already been decided. The stage version keeps that defiance intact.