The film's plot follows the story of Paikea Apirana ("Pai")[In the book, her name is Kahu, short for Kahutia Te Rangi], a 12-year-old girl who is the only living child in the line of the tribe's chiefly succession following the death of her twin brother and mother when she was born. By tradition, the leader should be the first-born son a direct patrilineal descendant of Paikea, aka Kahutia Te Rangi in the book, the Whale Rider he who rode on top of a whale from Hawaiki. However, Pai is female and technically cannot inherit the leadership.
Pai's koro, Apirana, or Old Paka as his wife Nanny Flowers calls him, the leader of the tribe, is initially angry at losing his grandson and being left with a "worthless" female. While he does later form an affectionate bond with his granddaughter, carrying her to school every day on his bicycle, he also resents her and blames her for many of the troubles facing the tribe. At one point Paikea decides to leave with her father because her grandfather is mistreating her. However she finds that she cannot bear to leave the sea as the whale seems to be calling her back, tells her father to turn the car back and returns home. Pai's father refuses to assume traditional leadership; instead he moves to Germany to pursue a career as an artist. Pai herself is interested in the leadership, learning traditional songs and dances, but is given little encouragement by her grandfather. Pai feels that she can become the leader, although there's no precedent for a woman to do so, and is determined to succeed.
Koro decides to form a cultural school for the village boys, hoping to find a new leader. He teaches the boys to use a taiaha (fighting stick). This is traditionally reserved for males. However, Nanny tells Pai that her second son, Pai's uncle, had won a taiaha tournament in his youth while he was still slim, so Pai secretly learns from him. She also secretly follows Koro's lessons. One of the students, Hemi, is also