Eternity and a Day traces the final days of Alexandre, a celebrated Greek writer as he prepares to leave his seaside home forever. While packing, he finds a letter from his long-dead wife, Anna, who wrote about an enchanted summer day they spent thirty years ago. From that point, Alexandre embarks on a mystical journey through his past and present. Realizing that after spending his entire life chasing after the words of poems and novels, Alexandre wants one final chance to capture the lost precious moments of true happiness, even if only for one day.