The narrative thread of the series "One August Night" unfolds from the murder of Anna Petraki (Evgenia Dimitropoulou) by her husband Andreas Vandoulakis (Yannis 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...

Manolis resolves to stand by Rinio for the last weeks of her life and begins to think about what will become of little Christina. The idea of raising her creeps into his mind, but he doubts whether he is capable of taking on such a life-changing responsibility. Meanwhile, Maria holds in her hands a mysterious letter from Andreas to Manolis, with unknown content. She wonders if she should mail it to Manolis or not, not knowing what unexpected developments this letter might bring. At the same time, Andreas is under pressure from Chronis and Stathakakis not to talk about what he saw during visiting hours on the day of the massacre. But maybe it's time to fight for some atonement, little as it may be.