Adam Hochberg, a young American WWII veteran with a pronounced limp, sits at a piano and recounts the story of his friend, Jerry Mulligan, arriving in Paris. Just after the liberation of France, US Army Lieutenant Jerry Mulligan explores the bustling streets of Paris and falls for a mysterious French girl (“Concerto in F”). Jerry decides to stay in Paris to nurture his passion for painting. He makes his way to a cafe/lodging house, where he meets and befriends Adam, a gifted pianist and fellow veteran. Henri Baurel, the son of wealthy French industrialists, enters to rehearse a nightclub act with Adam. Henri plans to run his family’s American branch while secretly pursuing a career as a nightclub star. He is also anxious about proposing to his girlfriend, whose name he will not reveal. The three men disagree over the role of art in the wake of war, but ultimately bond in friendship as they imagine a brighter future (“I Got Rhythm”).
Adam takes Jerry to the Paris ballet, where he accompanies auditions, to sketch the dancers. Jerry bumps into beautiful and headstrong American philanthropist Milo Davenport, who, struck by his talent and good looks, invites him to a party to introduce him to gallery owners. Henri’s mother, Madame Baurel, arrives with Ballet Director Maestro Z, introducing Milo as a potential donor. The audition begins and, to Jerry’s shock, the mysterious girl arrives. She dances beautifully, impressing the Ballet Director, Milo, Jerry and Adam (“Second Prelude”).
The girl introduces herself as Lise Dassin, daughter of famed ballerina Arielle Dassin, before hurriedly leaving for her job. Milo declares that she will fund the season only if the Maestro commissions a piece for Lise, with a score composed by Adam and designs created by the ‘noted painter’ Jerry Mulligan. Helpless at her charismatic hands, the maestro agrees, except for allowing Jerry to design the ballet—he has his own stable of designers. Infatuated with Lise, Adam sits down to write a ballet joining French and American culture.
Jerry finds Lise at her job at a perfume counter and tells her she got the job. Jerry does his best to charm her, and she agrees to meet him at the Seine that evening (“I’ve Got Beginner’s Luck”). Madame Baurel congratulates Lise, saying she is to be the prima ballerina of the Théâtre du Châtelet Ballet. Apparently, Lise lives with the Baurel family, which they have not disclosed to the Ballet in order to avoid charges of nepotism.
At the Baurel home, Henri attempts to write a letter proposing to his girlfriend, whom we learn is Lise. Meanwhile, Lise sits down at a cafe and writes a letter to her mother, who fled France and is presumed dead. Lise wonders whether she should marry Henri or take a risk on true love (“The Man I Love”). Adam, watching the scene from afar, falls more deeply in love with Lise.
Lisa meets Jerry on the banks of the Seine and tells him she cannot accept his friendship. He begs her to meet him every day so he can draw her until he gets it right. Both Lise and Jerry are haunted by events during the War, and in an attempt to put the pain of war behind them, they agree to meet as two friends, with Lise assuming a new name (“Liza”). Lise insists that Jerry never tell anyone about their meetings. Overjoyed, Jerry tries to kiss her, but she pushes him in the river. Still, they agree to meet the next day, same time, same place.
Henri remains stumped in his attempts to propose to Lise. His mother implies that his reluctance is perhaps due to a romantic interest in men. But Henri denies any such interest, and warns him that the family, vulnerable to accusations of collaboration with the Nazis, must consider appearances. When Lise arrives, Henri dodges the subject and tells her of his upcoming American tour. Lise offers to accompany him, and he takes this as an agreement to the proposal he has not yet made.
Back at the cafe, the three men rejoice over their love for Lise, singing a trio without realising they’re all thinking about the same woman (“S’Wonderful”). Henri shows the other two his proposal letter, only to find that he has Lise’s notebook by mistake. He reads the letter to her mother about her doubts over doing what is expected of her, marrying Henri and following her heart. Adam offers to console him with a drink while Jerry heads over to Milo’s party.
Jerry arrives at Milo’s apartment to discover that there was no party; Milo has invited him on a date on false pretenses (“Shall We Dance?”). Initially annoyed, Jerry relents after Milo gives him constructive criticism on his art and takes him to meet various gallery representatives. They begin a casual relationship.
Over the next week, Adam and Lise work on the new ballet, struggling with the material. Milo begins to fall in love with Jerry as they explore the Parisian art world, exploding with colour and new life. Meanwhile, Lise and Jerry find solace in their short daily meetings. Milo and Jerry attend a costume party, and Jerry is shocked to discover Lise there with Henri. Realising that Lise is engaged to his friend, Jerry explodes in a fit of rage and, with Lise watching, kisses Milo (“Second Rhapsody/Cuban Overture”).
The Baurels host an elegant party, where they’ve commissioned Adam to play, unaware of his connection to Henri. Jerry attends with Milo, but Henri, covering up his secret nightclub act, denies knowing them, arousing his parent’s suspicions. Jerry discovers that the party is a benefit for the ballet, and he fears that Lise will dance in the showcase performance. When Lise is not among the dancers, Jerry laughs in relief, causing a stir and eventually leading a wild dance number (“Fidgety Feet”).
After the performance, Lise appears as a guest of honour. The Baurels express an interest in hearing live jazz, and Jerry recommends the nightclub where Henri and Adam are booked to perform. The Baurels announce Lise and Henri’s engagement, crushing both Adam and Jerry, who lashes out at Milo and storms into the garden. Henri asks Milo to dance, and they bond as kindred spirits.
Lise confesses that she loves Jerry but cannot be with him because she is beholden to Henri for a reason she refuses to disclose. Jerry questions Henri’s love for her and begs her to meet him again. Lise tells him she does not have the luxury of love and runs away because “life is not like your American movies.” Jerry is left in despair as Milo, Adam, and Henri look on, having witnessed the altercation.
Back at their respective homes, they all act as if nothing has happened. In parallel conversations, Milo and Henri question Jerry and Lise, seeking honesty (“Who Cares?/For You, For Me, For Evermore”). Henri pledges his love for Lise, but Jerry decides to be honest with Milo and breaks things off. Adam and Milo reflect on the love around them, wondering why they remain alone (“But Not For Me”).
In a nightclub in Montparnasse, Adam and Henri prepare for one of their final performances. Adam begs Henri to let Lise stay in Paris and accuses him of being a coward both during the war and afterwards. Henri, furious, admits the truth: Lise is beholden to Henri because he and his family saved her life during the occupation. She was the daughter of the Baurel’s Jewish butler, and she was entrusted to their care after her parents were arrested by the Nazis. Henri threw himself into the Resistance, all of them risking their lives for her, and have kept this secret due to the disruption this would cause their social status in the fragile post-war world. Adam asks if that means that Lise has to throw away her life to pay Henri back when neither of them really love each other. He begs Henri to find the courage he had during the war, freeing Lise to make her own decisions.
Jerry sees Lise at the nightclub. He tells her that he and Milo are through and begs her to tell him what obligations she has to Henri, but Henri’s act starts. Henri’s act begins and he is stricken with nerves, but Adam encourages him to remember his dream, and he fantasizes of performing an elegant number in Radio City Music Hall (“I’ll Build a Stairway to Paradise”). His act ends triumphantly, until he realises his parents were in attendance.
Mme Baurel berates him for shaming the family name, but Mr. Baurel is proud and in awe of his son’s talent, and she capitulates. Lise, however, is angry at Jerry for accidentally exposing Henri. She leaves and Jerry, trying to run after her, accidentally knocks Adam to the ground. When he tries to help him up, Henri stops him, furious for disrupting his relationship with Lise. Jerry accuses Henri of being a coward, and Henri punches him. Adam tells Jerry about Lise’s past and Henri’s involvement in the Resistance. Jerry, determined to keep fighting for love, tells Henri that if he chooses duty over love, they are all doomed. Lise, who has overheard the confrontation, comes back in, telling Henri to take her home. Jerry pleads with her, but she departs, leaving him heartbroken. Adam has a flash of insight: if life is dark, then it is an artist’s duty to celebrate and bring love back into life. He feverishly revises the score for the Ballet, turning it into a celebration of life.
On opening night at the Ballet, Jerry shifts nervously outside Lise’s dressing room, a scroll in his hand. Milo, seeing his indecision, offers to deliver it for him. Lise opens the scroll to find that it is his drawing of her, finally complete. Milo confesses that Jerry did teach her one thing: money cannot buy love, which is one of a kind. Lise thanks Milo, but confesses that she knows the ballet will fail; she is so upset that she has lost her passion onstage. Milo advises her to think of someone who made her feel that passion as she dances. Lise clutches Jerry’s drawing tight as places are called. The ballet begins, and as it progresses, Lise imagines her partner has become Jerry, and they perform a magnificent pas de deux. The ballet ends with Lise triumphant, having become a bona fide star (“An American in Paris”).
After the curtain call, Jerry apologises to Lise, who admits she wouldn’t have danced as passionately if she didn’t love him. Henri admits to his new confidante Milo that he can’t tell if his love for Lise is out of duty or passion; he asks Lise to take a drive with him. Milo approves, asking Henri to call her the next day. Lise gives Adam a rose from her bouquet and kisses him good-bye. Adam, glowing amid wonderful reviews and audience adulation, realises he loves Lise not for herself, but for the light she brings into the world. The three men, grateful for the lessons they’ve learned vow to always remember Lise (“They Can’t Take That Away From Me”).
Jerry sits alone by the Seine. Lise appears; she has decided to follow her heart. They dance together and walk off into the Paris night (“Epilogue”).