Thirty-seven-year-old Loretta Castorini, an Italian-American widow, leads a simple life as a bookkeeper in Brooklyn Heights. She resides with her parents, Cosmo and Rose, as well as her grandfather. One day, Loretta's boyfriend, Johnny Cammareri, proposes to her just before departing for Sicily to care for his ailing mother. While she accepts, she feels a strong compulsion to adhere to tradition, convinced that neglecting such customs contributed to her first husband's untimely demise just two years into their marriage.
Johnny requests that Loretta extend an invitation to his estranged younger brother, Ronny, for their wedding. It's been five years since Ronny and Johnny last spoke. Eager to share her happy news, Loretta returns home to inform her parents about her engagement. However, Cosmo, who runs a thriving plumbing business, harbors a deep disdain for Johnny and is hesitant to fund Loretta's envisioned "real" wedding. Upon realizing that Loretta is fond of but does not truly love Johnny, Rose shares her wisdom, suggesting that genuine love carries the risk of emotional hurt between partners.
Determined to resolve family tensions, Loretta goes to Ronny's bakery, where she discovers that he has a wooden prosthetic hand, a result of a past incident involving a bread slicer while he was talking with Johnny; this mishap led to his fiancée leaving him. Pressing for a more personal discussion, Loretta and Ronny head to his apartment, where she prepares a meal and they indulge in drinks. During their conversation, Loretta likens Ronny to a wolf who would gnaw off its paw to escape a snare, implying that he deliberately harmed himself to break free from a toxic relationship. In a passionate moment, Ronny kisses her, and to her surprise, Loretta reciprocates. Their connection deepens, and Ronny carries her to bed, where they share an intimate night together.
That evening, as Rose hosts her brother Raymond and his wife Rita for dinner, they grow concerned about Loretta's whereabouts. Raymond reminisces about a luminous moon that shone during his courtship of Rose, an image that Loretta and Ronny also witness. The following morning, guilt overwhelms Loretta, but Ronny assures her that he won't burden her anymore, provided she joins him for a performance of La bohème at the Met. Loretta attends church to seek forgiveness for her infidelity and afterwards drops by Raymond and Rita's store to settle the cash register. On a whim, she decides to visit a hair salon and splurges on an elegant evening gown and shoes.
Stirred by the beauty of La bohème, Loretta is drawn outside, only to confront Cosmo, who arrives with his mistress Mona. Pressured by her emerging feelings for Ronny, Loretta wrestles with the temptation of keeping their encounter a secret. Despite her attempts to return home, Ronny ardently convinces her to engage in yet another romantic escapade. Meanwhile, Rose dines alone at a restaurant and encounters a distraught college professor named Perry, whom she takes pity on, inviting him for supper. They share a pleasant evening, though Rose remains dedicated to her marriage, leaving Perry at her doorstep.
The next day, Loretta is alarmed to hear from Rose that Johnny has returned from Sicily after his mother's unexpected recovery, leading to a meeting with Rose at the Castorini home. They find common ground in discussing how men chase women driven by a fear of mortality.
When Loretta returns home the following morning, anxiety grips her with the news that Johnny will soon arrive. Ronny appears, and despite her protests, Rose invites him for breakfast. Grandpa and Cosmo join them, with Grandpa insisting Cosmo must finance Loretta's wedding. Rose, determined and unyielding, confronts Cosmo about his affair, pushing him to confess. Their dialogue renews their love, creating a moment of solidarity.
Concerned about Loretta’s banking oversight, Raymond and Rita stop by to check on her but are relieved to learn that it was merely a forgetful moment. Ultimately, when Johnny arrives, he shatters the engagement by claiming that their marriage would bring death to his mother. Enraged, Loretta chastises Johnny for breaking his word and hurls the engagement ring at him. Seizing the opportunity, Ronny asks Loretta to marry him instead, to which she joyfully agrees. The family raises their glasses in a toast to the new couple, with Johnny, encouraged by Grandpa, reluctantly joining the celebration, now embraced as part of the family.
