The main characters Jesse and Celine met in their twenties in Before Sunrise and reunited in their thirties in Before Sunset. In the third part of the trilogy, they are the parents of twins and Jesse's son from his first marriage.
Their idyllic love from the first two parts is marred by reality dictated by children, work, ambitions, disappointments, fluctuations and efforts to develop their relationship. Before the clock strikes midnight, they must face their past, present and future, their family and their love.