Martin is a domestic white goose from the Holgersson family farm in southern Sweden. Initially subjected to Nils's mistreatment before the boy's magical transformation, Martin harbors a deep-seated yearning for freedom and adventure beyond the farm’s boundaries.

When a migrating wild goose flock flies overhead, Martin impulsively joins them, defying his domestic nature to take flight. This choice launches his odyssey across Sweden. During migration, he confronts skepticism from the wild geese about his origins and must repeatedly demonstrate his stamina and flying prowess to stay with the group.

Martin navigates a complex dynamic with Nils, who travels alongside him. Wary at first due to their troubled past, he gradually forges a bond of mutual dependence and teamwork with the boy. Their alliance proves vital in overcoming challenges like predators and severe weather. Martin extends his protective instincts beyond Nils, aiding the flock’s efforts against persistent threats such as the fox Smirre.

His character transforms during the journey. Martin exhibits resilience in adapting to long flights and wilderness survival, evolving personally through a pair bond with Dunfin, a wild goose. This relationship cements his integration into the goose community and commitment to their migratory life.

Martin’s role shifts from outsider to valued flock member, contributing to group decisions and defense. His journey embodies themes of transformation, belonging, and reconciling domestic roots with wild aspirations, culminating in acceptance by wild goose society while preserving his distinct identity.