"The Green Vessel" tells the journey and the story of an old man on a river. Like a storyteller, he shares with us a story: the tale of a scientist who discovers a contaminated river and tries to understand the sources of this problem. Accompanied by an artist and a young guide, he pursues his research in remotes territories covered by a large forest. As the old narrator continues his tale, he engages himself in a long journey between river and vegetation, a quest that connects him to his own story.