1985. Eleven adventurers set out on the first-ever attempt to descend the Amazon — from its source to the Atlantic Ocean. What begins as a final rite of passage before adulthood quickly turns into a test far beyond anything they anticipated. As the expedition unfolds, it becomes clear that the greatest challenge is not the untamed river but the volatile mix of emotions, conflicts, and a relentless struggle for leadership. Four decades later, the participants look back on this pioneering journey, confronting their memories and asking a question: what is more unpredictable — nature or people?

Anna is a teacher and her husband Marek is an engineer. They both face moral dilemmas at work: Marek's boss wants him to help get rid of a renowned engineer from their company; Anna refuses to support the false accusation of her student.