Just as Kate was busy preparing for their 45th wedding anniversary, her husband Geoff suddenly received a message that brought his thoughts back to the past: the body of his girlfriend, who died in an accident in the Swiss Alps 50 years ago, had been found. Both Kate and Geoff were deeply shaken but unable to communicate their hidden anxieties to each other. Geoff shut himself off in a world of memories, while Kate struggled to suppress her jealousy and anxiety, needing to focus on preparing for the party, arranging music, the menu, and other similar things. On the surface, everything seemed normal, but the camera keenly captured the gradual imbalance in their once harmonious coexistence. Whether having breakfast with Geoff or strolling alone in the town, Kate felt increasingly like a stranger. In '45 Years', the couple is seized by unexpected emotions and forced to confront unfamiliar feelings, and in this process, their once happy times seem to have vanished. After living together for 45 years, which emotion will prevail on their wedding anniversary?