Stjarnán is a young troll who lives in the mountains of Carrantuohill, Ireland. Fascinated by the stars since childhood, he spends his nights observing the sky and trying to unravel its mysteries. His younger brother, Caelan, always accompanies him on his nighttime excursions, although he still does not understand why the stars are so important.

One night, Stjarnán discovers a mysterious lone star that seems to guide them toward a hidden secret. The brothers embark on a magical adventure to discover the truth behind the constellations and find an ancient map that connects the sky and the earth.

Together, they learn about the importance of sharing knowledge and experiencing brotherly adventure.