An orphaned baby boy is found in a beached canoe after a violent storm and is taken in by Malio Rawiri Paratene, the island chief. Malio names the boy Tama Joe Folau and vows to raise him as his heir, even though he already has a son. The chief's wife quickly begins to spread rumors that Tama is sent from the trickster god to bring trouble. A string of unlucky incidents convinces Malio that Tama is cursed, and the once-loved child becomes an outcast, passed from family to family around the island. At one point, a drunk villager, Pioi Hori Ahipene, takes Tama in. He has a daughter named Mahana Kayte Ferguson, who is deemed ugly by others but remains kind and forms a quiet friendship with Tama.
Tama, worn down by life as an outcast, decides to leave the island in a canoe he builds, and before he goes he promises Mahana that he will come back and care for her. A violent storm drags him to the shore of another island, home to Johnny Lingo George Henare, a well-known Polynesian trader who treats Tama with warmth despite the years of rejection Tama has endured. Tama’s guarded nature meets Johnny’s openness, and Tama, suspicious of Johnny’s gruff chief steward, chooses to leave rather than stay. He also makes a misstep by stealing jewellery from Johnny’s treasury, an act that lands him a seven-year sentence to work off his debt.
During those years, Tama uses his ingenuity, inventing simple machines that help him finish tasks faster and win Johnny’s respect through steady, honest effort. Eight years pass, and Johnny plans to take Tama to a nearby island to seal an important trade. The journey is rocky; Tama offends the islanders and Johnny is taken hostage, forcing Tama to return to Johnny’s home to secure a ransom—an entire cow from Johnny’s herd—thereby earning the trust of Johnny’s chief steward in the process. Tama, Johnny, and the chief steward are later honored at a wedding on the neighboring island, where Tama learns that he is the actual heir to that island’s chiefdom. He initially contemplates accepting the title but soon realizes he is happier working alongside Johnny. After they return home, Johnny confides that he is dying and entrusts Tama with his name and fortune.
As the new Johnny Lingo, Tama sends the chief steward ahead to Malio’s island to discover what has happened to Mahana. He then arrives himself and announces that he intends to choose a bride from among the island’s young women. A grand feast is planned for that night, but Mahana is not present. Tama goes looking for her and she eventually meets him on the way, still angry and not recognizing him as the boy who left years ago. The next day, she reveals that she waited for Tama every day for eight years, doubting his return and growing to hate him. Tama refuses to give up and offers to barter with Pioi to win Mahana’s hand, hoping to prove his devotion.
At the bartering ceremony, Pioi, whose health has deteriorated badly, asks for two cows as Mahana’s dowry, which would be the richest in island history. Tama counters with eight cows, a gesture that shocks Mahana into silence. She initially fears Tama is mocking her, and she storms off, but outside the hall the eight cows stand as a testament to Tama’s sincerity. Mahana’s fury turns to recognition when she discovers the armband she gave Tama years earlier on his arm, proving that the boy she waited for is the man before her. She confronts him, feigns anger at the long absence, and then accepts him with a heartfelt embrace. The film closes with Tama recounting the remarkable journey to a writer, surrounded by his joyful, now full family.
