Trio is a young boy residing in a small village bordering a forest, living with his mother and his pet cat, Coda. Their close bond is underscored by his mother singing lullabies to him at night. When invading Nazi-like soldiers attack and destroy his village, Trio and Coda witness the brutal destruction firsthand. During the assault, soldiers capture Trio on a bridge and throw him into the river, forcibly separating him from Coda and his mother.

Trio survives the river ordeal but emerges as a war orphan. He eventually joins a gang of thieves, led by Black Jack and composed of other war orphans. Within this harsh existence, Trio develops a cynical view of the Bremen 4 musicians after observing them perform for elite collaborators. He confronts them, accusing them of being media-hungry opportunists indifferent to the plight of the oppressed.

Later, soldiers under Colonel Karl Presto capture Trio and bring him to Presto's castle. Trio identifies Presto as the officer who ordered the massacre on the bridge and commanded his drowning, thereby exposing Presto's crimes. Trio is imprisoned alongside the Bremen 4 and Adagio. He escapes through a dungeon sewer with their assistance, riding Largo after the donkey returns to animal form.

Trio survives the conflict and is adopted by Adagio following the defeat of the invaders. His journey reflects the impact of war on children, tracing a path from vulnerability through survival-driven skepticism to eventual stability.