In the picturesque coastal town of Mystic, Connecticut, three vibrant young women—Kat Araújo, her sister Daisy, and their close friend Josephina "JoJo" Barboza—infuse life into the lively streets. Working as waitresses at Mystic Pizza, a cherished eatery owned by Leona and her husband Vic, these Portuguese-American women craft their own distinct narratives.
For JoJo, the excitement of impending nuptials leads to an unexpected bout of nerves, resulting in her fainting on her wedding day. Despite her concerns, she yearns for the intensity that comes with romance. Her boyfriend Bill, however, grows tired of her indecisiveness and chooses to move on. The sisters, on the other hand, are polar opposites. Kat, with dreams of being an astronomer, strives for intellectual growth and consistency, juggling jobs at both the planetarium of the Whaling Museum and Mystic Pizza. Meanwhile, Daisy embraces life with a free-spirited attitude and a thirst for thrill.
As the sisters carve out their own journeys, Kat discovers comfort in her developing relationship with Tim—a charming architect and Yale alum who hires her to care for his daughter Phoebe. Initially hesitant, Kat comes to see her bond with Tim as true love. In contrast, Daisy’s fleeting romance with Charles—a wealthy young man she encounters at a bar—comes to a sudden halt when his relatives make insensitive remarks about her Portuguese background. Hurt and betrayed, Daisy accuses Charles of manipulating their relationship to rebel against his family.
As the women navigate their personal challenges, Kat's relationship with Tim creates friction between the sisters, with Daisy feeling criticized for her more adventurous lifestyle. However, when Tim's wife Nicki unexpectedly returns, Kat's illusions of love are crushed, leaving her heartbroken. In a touching moment of solidarity, Daisy comforts her grieving sister, reinforcing their emotional connection.
In a twist of fate, the sisters, alongside JoJo and Leona, experience an unexpected visit from a famous television food critic known as "The Fireside Gourmet." The critics take a bite of a pizza slice and scribbles notes before leaving. Although his fleeting endorsement could significantly boost Mystic Pizza's popularity, the women remain cautiously hopeful for the future.
As days pass, Tim accompanying Phoebe to Mystic Pizza becomes a bittersweet farewell for Kat, who is preparing to leave her hometown. In a generous act, Tim gives Kat a check meant to ease her tuition struggles, but her reaction is surprising. Moments after the Fireside Gourmet’s review airs on television, awarding the pizzeria an outstanding 4-star rating and praising its "superb" pizza, Kat tears the check into pieces. As a result of the glowing review, Mystic Pizza's phone starts ringing off the hook, delighting Leona with her infectious laughter as she assures callers that no reservations are required.
Meanwhile, JoJo and Bill celebrate their marriage, marking an important milestone, while Kat chooses an alternative path by accepting a loan from the kind-hearted Leona to further her education. The wedding also proves to be a moment of healing for Daisy and Charles, who decide to set aside their differences amidst the joy of love and celebration.
As the film draws to a close, the three women gather on a balcony overlooking the water, their faces illuminated by the nostalgic glow of shared memories as they reflect on their journey together and ponder the uncertain future that lies ahead.
