"Ngày Xưa Có Một Chuyện Tình" revolves around the intertwined friendship and love story of two boys and a girl from childhood to adulthood, as they face the challenges of fate. Spanning four stages from 1987 to 2000, the three friends—Vinh, Miền, and Phúc—grow up together, experiencing the innocence of love, life's struggles, and personal growth along the way.