The American girl, named Sophie, is a fact-checker for The New Yorker and is on a pre-honeymoon trip with her fiancé. While exploring Verona, the city of Romeo and Juliet, Sophie discovers a group of women who call themselves the "secretaries of Juliet." These women respond to letters written to Shakespeare's tragic heroine, Juliet, seeking advice on love and life. Sophie volunteers to help answer letters and stumbles upon a 50-year-old unanswered letter hidden under Juliet's balcony.
The letter is from Claire, a British woman, who fell in love with an Italian man named Lorenzo during a trip to Verona in the 1950s. She never heard back from her lover and has regretted not staying in Verona ever since. Touched by the letter, Sophie sets out to find Claire and reunite her with Lorenzo.
With the help of Charlie, Claire's grandson who is initially skeptical of Sophie's plan, the trio embarks on a romantic journey through the picturesque countryside of Tuscany to track down Lorenzo. Along the way, they visit vineyards and enjoy delicious Italian cuisine, falling in love with the culture as well as each other.
Sophie's journey not only helps Claire find her long lost love but also gives her the courage to follow her heart and marry her own fiancé. The film ends with a beautiful reunion between Claire and Lorenzo and Sophie realizing her true feelings for Charlie.