Kellou, in her forties, lives in Bol, the capital of Sahel’s province. She’s a fisher, profession transmitted from mother to daughter. She learned it from her mother. But since a few years, Lake Tchad has been shrinking, and fish has become rare. Kellou’s job is threatened. One day, after an un- successful catch, her 12 year old daughter Mouna gives her an idea: pick up plastic bags invading the lake and make ropes out of it to sell them on the market. By this simple gesture, Kellou gets to, in her own way, fight against plastic pollution and adapt to the new conditions brought about by climate change.

There is not only fresh air in Black Lake, there are also very mysterious things happening there... Valérie, a police officer from town, arrives with her son Dave to assist Adrien, the chief of police of a small village whose partner has been missing for 3 weeks.

Bénédicte and Charles-Thomas, two ambitious city hall employees, invent a sea monster to attract tourists to Saint-Jean-du-Lac. And the best part is that it works! Their video of the "monster" goes viral, and hordes of curious onlookers come to the little village.