Plot
The opening scene shows Taylor and her boyfriend, Raf, by the sea. Raf wants Taylor to stay with him in Italy, but Taylor wishes to go to university and start her "real life".
Three years later, Taylor goes to the south Italian region of Apulia on holiday ("Holiday"). Her sister Maddie, who went there five weeks before upon Taylor's instruction to get over a break-up with her boyfriend Doug, greets her when she arrives and surprises Taylor with her extravagant house and their friend Lil. Maddie also reveals she is getting married in two days, which shocks Taylor ("Venus"). Lil reveals that Taylor had a boyfriend in Apulia on her holiday three years ago, but Taylor explains she doesn't want to rekindle her relationship with him. Taylor then goes down to the beach to see if she recognizes anybody from her holiday three years ago. She is reunited with her friend Elena and her boyfriend Enrico, as well as her friend Mikey. Taylor sees Raf on the beach and follows him cleverly ("How Will I Know?") before falling right in front of him. Raf recognizes her and is about to greet her when Maddie runs over and kisses Raf, revealing that Raf is Maddie's fiancé. Raf, Elena, Mikey and Enrico are all very surprised that Maddie and Taylor are sisters as they don't think the pair have anything in common. Taylor is shocked that Maddie is marrying Raf, but pretends she doesn't know him, Elena, Enrico, or Mikey, despite Elena telling her she should tell Maddie the truth. Taylor declines, and tells her she would prefer to keep it a secret as not to worry Maddie.
Later on that night the group attends a dinner, where Raf makes a speech about Maddie that brings Taylor to tears, which she disguises. Maddie makes a speech ("The Power of Love"). Taylor goes outside to the bar and Raf follows her, saying that the relationship between them is "weird", which Taylor denies at first but then agrees with. Raf wants to tell Maddie about their relationship three years ago but Taylor refuses, wanting to protect Maddie and to stop her from feeling like a fool.
The next day, Raf and Taylor are sent by Maddie to go and sort out their clothes and also the rings. Raf and Taylor argue about their past relationship and Taylor says she doesn't believe people should "sing from the rooftops", referring to people's feelings. Raf argues that if they do, they really mean it. Elena, Mikey and Enrico overhear and leave. However, when Raf and Taylor step out of the changing cubicles in their wedding outfits it is hinted that they still have feelings for each other.
While this is happening, Doug turns up and surprises Maddie at the market. He tells her he made a mistake by breaking up with her, and wants her back. She declines, but Doug tries to persuade her ("Don't You Want Me"). He follows Maddie back to her house, where she agrees to have dinner with him before her hen party as a "final farewell". Elena and Enrico are discussing Taylor's secret by the pool and Maddie walks in, finding out Elena has a secret. Elena panics and tells her she is pregnant.
Raf and Taylor return from wedding preparations and Maddie asks if Taylor would like a plus one, hinting at her past boyfriend from three years ago. Taylor declines and then finds out about Doug and Maddie's dinner after Doug sends Maddie pink roses with a note saying he can't wait for it, and an argument ensues. The others break up the argument by taking Taylor to the tomato festival ("Walking on Sunshine"). Maddie is left behind to be pampered for her hen night.
After the festival, Raf takes Taylor to the sea to wash off the tomatoes. The sun is setting ("Eternal Flame"). Raf overhears Taylor and the two go to kiss, but Taylor runs away, still thinking about Maddie. Raf chases her as she runs back to the house, and he demands to know if she has any feelings for him and to discuss what happened between them on the beach. Whilst they are arguing, Maddie walks in and her hen party guests led by Elena and Lil surprise them. Taylor is forced to reveal that Raf was her old love from her past Puglia holiday but lies, saying that she has no feelings for him. Raf is hurt, but says the same, to keep his relationship with Maddie strong. Lil kicks Raf out of the hen night and Maddie tells Taylor to change for the party.
The girls go out on the hen night, dressed up ("Girls Just Wanna Have Fun"); the boys do the same ("The Wild Boys"). Taylor leaves the nightclub that the girls are visiting, and sings It Must Have Been Love, along with Raf who is in a different part of Puglia at his stag do. Taylor realizes she still loves Raf and decides she can't stay in case she destroys Maddie and Raf's relationship. She leaves for the airport in a taxi, throwing a picture of her and Raf out of the taxi window.
Whilst Taylor is leaving, Maddie goes back to her bedroom where Doug is waiting. He says he does not want anything from her but he wants to give his blessing, which Maddie says is "sweet" before she realizes what Doug is doing. She ties Doug up, pretending she is going to have sex with him ("Faith"); instead, she pushes him into the pool. Everything goes silent and Maddie goes to see if he is alright, and Doug is on one knee with an engagement ring, which confuses Maddie.
The morning afterwards, Lil finds Taylor in the airport and offers advice. She says that Taylor must forget her feelings for Raf as her relationship with Maddie is more important. Taylor agrees and the pair get in a taxi to go to the wedding, after Lil realizes they are late. Taylor changes in the taxi. Maddie also wakes up late, hugging a picture of Raf, meaning she turned Doug away. Raf is shown duct taped to a tree next to a nunnery. The cast congregates at the church ("White Wedding"). Maddie and Taylor reconcile before heading inside.
At the altar, the priest asks if anybody objects to Raf and Maddie's marriage, to which Doug stands up, but Maddie tells him to sit down. Maddie then surprises everyone, telling Raf she is in love with love itself rather than him specifically and that he deserves better. Raf leaves the church but Taylor pursues him to apologize ("If I Could Turn Back Time"). When it doesn't work, Taylor runs to the roof and sings to Raf from there, as earlier on in the film Raf said if somebody sings from the rooftops you can tell they mean their feelings. Raf joins Taylor on the roof where Taylor tells Raf she loves him and the two kiss.
Later at the beach, Elena admits to Enrico that she actually is pregnant and Enrico is overjoyed. Lil hints at having feelings for Mikey by kissing him. Maddie and Taylor discuss how Maddie is now alone, but she says she will be fine. Doug interrupts the girls, and Lil and Taylor strap him into a hang glider whilst Maddie distracts him. Lil gives a signal to a boat offshore and Doug is flown up into the air, screaming. The entire cast then perform "Wake Me Up Before You Go-Go" and the film ends.
