On July 15, 1988, recent graduates Emma Morley and Dexter Mayhew spend the night together after their graduation from the University of Edinburgh. Though they decide not to pursue a romantic relationship, they form a strong bond and agree to remain friends. Over the next few years, Emma grapples with her unfulfilling jobs and failed attempts at becoming a writer, while Dexter travels around the world, indulging in a hedonistic lifestyle as a television presenter. Despite the distance and their contrasting lives, they continue to stay in touch and their connection deepens.

As the years pass, Emma eventually finds her footing as a teacher and begins a relationship, while Dexter deals with his declining career and personal issues. Every year on July 15, the film revisits their lives and their evolving relationship, depicting their struggles, growth, and enduring bond. Their interactions are filled with emotional moments as they navigate the complexities of their relationship and individual lives. Their story is a poignant exploration of friendship, love, and the impact of time.