American fund manager Millie Cantwell, whose life-long dream is to become an opera singer, quits her lucrative job in London just after being offered a promotion. Deciding to take a year to make it, she moves away from her boyfriend Charlie and travels to the Scottish Highlands for intense vocal training from former opera diva Meghan Geoffrey-Bishop.
Patricia Hartley from the London conservatory suggests Millie contact the retired diva to train for the annual competition Singer of Renown in hopes of winning a spot in an opera company. She convinces her to give her an audition by offering a very high hourly rate for lessions. Her only other student Max Thistlewaite who, unable to pay in cash, works around her cottage.
Arriving in the tiny Scottish town, Millie again convinces the pub The Filthy Pig owner Ramsay to give her a room by mentioning a prolonged stay. Max also works in the pub, and is very agitated upon discovering his direct competition.
As Millie sits in the pub, Max is openly hostile towards her. The half dozen patrons openly discuss his possibility to 'lift the curse'. In the morning, Max intentionally interrupts her audition by opening the spigot by the window. Evenso, after trying to break Millie down, Meghan offers to train her.
On the morning of her first lesson, Millie discovers Max is Mrs. Geoffrey-Bishop's other student. She asks Ramsay about Max, who has been there training under her for five years. He also will be trying to win the competition, his third and last attempt. When Millie asks Ramsay if the diva has only taken her on for the money, he points out that the whole village's income is mostly from her.
Meghan's harsh methods hurt both Millie's tongue and vocal chords. Max, seeing her pain, brings her a jug of warm salted water to gargle with. Ramsay, after hearing Millie sing in her room, approaches Meghan to suggest she not be so harsh. When Max asks, Meghan suggests the competition could be good for him as she sees potential in Millie.
Max coaches Millie a bit, and shares some books on voice theory. They both participate in an Edinburgh recital and a critic highly praises Millie while noting that Max's singing lacks feeling. Meghan has them work on a duet together, so just as they are about to connect Charlie calls. He has come for a surprise visit. Max is visibly upset, as Charlie stays the night with Millie.
Practicing the duet in front of Meghan the next day, she points out the piece would be more effective if they sang it to each other, although it did bring tears to her eyes. Afterwards, Millie apologises to Max for Charlie's interruption of their rehearsal and asks him not to tell Meghan about her visitor. When he asks if they are engaged, she vehemently insists not.
When Meghan notices Max seems interested in Millie, she suggests he go away for a bit so that Millie misses him. It seems to work, as when he returns in a few days to celebrate both of them being accepted to compete in Singer of Renown, they start to fool around, but Millie insists they stop. She also believes they should have no contact until after the competition.
Millie is the fifth of the 15. As she departs the stage, Max approaches her on bended knee. Overwhelmed, Millie runs off to the restrooms. Meghan follows, then insists she give an answer. Millie hands her the ring box, to which their teacher replies Max will either sink or swim. He ends up winning.
Three years later, the now established Max finds his counterpart in Don Giovanni is ill, so Millie is one of his two options. She tells him her relationship with Charlie ended when she did not return to work with him. Max and her performance is successful.
