The narrative thread of the series "One August Night" unfolds from the murder of Anna Petraki (Evgenia Dimitropoulou) by her husband Andreas Vandoulakis (Yiannis Stankoglou), one night in August, six years ago, when the latter learns that she had a lover, his cousin Manolis Vandoulakis (Yorgos Karamihos).
The main role in the series is played by Anna's sister, Maria Petraki (Youlika Skafida), who tries to continue her life, keeping well-hidden secrets that must not come to the surface...

The unexpected meeting between Manolis and Antonis revives the past and brings to the surface what the two old friends never told each other, but also themselves. At the same time, the death of Alexandros Vandoulakis triggers the conflict between his daughter Olga and Maria's family, but the outcome will take everyone by surprise. Meanwhile, Andreas is intrigued by an enigmatic prisoner, Chronis, who claims to be a priest. Agathi is disappointed by the behavior of Stavros, who, although he had begun to flirt with her, suddenly and for some mysterious reason now avoids her.