A thirty-something busker (Guy) performs with his guitar on Grafton Street, a Dublin shopping district and chases a man who steals his money. Lured by his music, a young Czech flower seller (Girl) talks to him about his songs. Delighted to learn that he repairs hoovers, Girl insists that Guy fix her broken hoover. The next day Girl returns with her broken hoover and tells Guy that she is also a musician.
At a music store where Girl regularly plays piano, Guy teaches her one of his songs (“Falling Slowly”); they sing and play together. Guy invites her to his father’s shop, and on the bus home musically answers Girl’s question about what his songs are about: a long-time girlfriend who cheated on him, then left (“Broken Hearted Hoover Fixer Sucker Guy”).
At the shop, Guy introduces Girl to his father and takes her to his room, but when he asks her to stay the night, Girl feels insulted and leaves. The next day, they reconcile and spend the week writing, rehearsing and recording songs. Girl rehearses lyrics for one of Guy’s songs (“If You Want Me”), singing to herself while walking down the street; at a party, people perform impromptu (including “Gold”).
Guy works on “Lies”, a song about his ex-girlfriend, who moved to London. Girl encourages him to win her back. Invited to the woman’s home, Guy discovers that Girl has a toddler and lives with her mother. Guy decides to move to London, but he wants to record a demo of his songs to take with him and asks Girl to record it with him. They secure a bank loan and reserve time at a recording studio.
Guy learns Girl has a husband in the Czech Republic. When he asks if she still loves her husband, Girl answers in Czech, “Miluji tebe” (“I love you”), but coyly declines to translate. After recruiting a band from other buskers, they go into the studio to record. They impress Eamon, the jaded studio engineer, with their first song (“When Your Mind’s Made Up”). On a break in the early morning, Girl finds a piano in an empty studio and plays Guy one of her own compositions (“The Hill”).
After the all-night session wraps up, they walk home. Before they part ways, Girl reveals that she spoke to her husband and he is coming to live with her in Dublin. Guy persuades her to spend his last night in Dublin with him, but she stands him up and he cannot find her to say goodbye before his flight. He plays the demo for his father, who gives him money to help him get settled in London. Before leaving for the airport, Guy buys Girl a piano and makes arrangements for its delivery, then calls his ex-girlfriend, who is happy about his imminent arrival. Girl reunites with her husband in Dublin and plays the piano in their home.