Summer 2016, somewhere in French provencal Drôme, a mysterious plague strikes in the villages: swarms of white butterflies invaded the area. At dusk, everyone is locked up home, trapped by the seemingly unstoppable vermin. As the big swarm approaches, Lou discovers both the strange insects and her feelings for her friend Sam. By the end of the season, the moths will have devastated the entirety of the century-old box trees, leaving a ruined landscape behind them.