Geronimo Stilton travels to the mysterious Happy Isles Atoll to investigate a strange mystery — huge footprints have been discovered in the forest, and no one knows what creature made them.

According to legend, giants once lived on the island, and some locals believe they may have returned. Geronimo, with his usual mix of curiosity and clumsiness, sets out to uncover the truth behind the legend. Along the way, he faces exciting adventures, funny situations, and unexpected discoveries about friendship, courage, and believing in the impossible.