Black Grass tells the story of a group of young people who discover a secret organisation that plans to put an end to civilisation using a new species of plant. Starting with a new species of grass, modified in a laboratory and commercialised as a kind of drink, the organisation wants to take control of society. In a daring battle against the clock in which nothing is what it seems, the protagonists will have to piece together various clues in a kind of brain teaser to save the world and everything they hold dear.