Set in late 19th-century Budapest, the story revolves around a gang of working-class boys who fiercely protect their makeshift playground — the GRUND — from a rival group of wealthier boys known as the Redshirts. At the heart of the narrative is Nemecsek, the smallest and weakest boy in the gang, who exemplifies quiet courage and a strong sense of justice.

As tensions rise, the boys confront not only external conflicts but also the challenges of growing up, including betrayal and sacrifice. The musical features a rich score that blends pop-rock with lyrical ballads, capturing the delicate transition from childhood idealism to the harsh realities of life.