In a dystopian near future, single people, according to the laws of The City, are taken to The Hotel, where they are obligated to find a romantic partner in forty-five days or are transformed into animals and sent off into The Woods.

It follows the story of Mickey and Chloe, two Americans in their mid-thirties living in Athens, who meet in the heat of summer one whirlwind weekend. When Chloe's time in Greece is drawing to a close, she decides to give up her high-flying job back home and explore whether one weekend's passion can stand the reality of the inevitable Monday.

Jesse and Celine first met in their twenties, as seen in Before Sunrise, reunited in their thirties in Before Sunset and, now they face the past, present and future, family, romance and love. Now on a writer's retreat in Greece, the couple looks for a night of passion, but instead their idyllic night turns into a test of their relationship and a discussion of what the future holds for them.