Farmer Michel Villeneuve is diagnosed with leukemia after collapsing in a field he'd just sprayed with a weed killer made by the agrochemical giant Saskia. His childhood friend Guillaume Delpierre, a principled politician, crusades to get the pesticide banned, with help from his ambitious assistant Romain Corso. They have to square off against Mathieu Bowman, a hard hitting lobbyist hired by Saskia. But when Saskia's Head of Marketing is found floating in the Seine, his daughter Chloé launches a behind-the-scenes investigation with help from former journalist Claire Lansel, who has recently been recruited to Bowman's team.