Set in and around the fictional town of Kapua in 1948, Ngāti is the story of a Māori community. The film comprises three narrative threads: a boy, Ropata, is dying of leukaemia; the return of a young Australian doctor, Greg, and his discovery that he has Māori heritage; and the fight to keep the local freezing works open.

In a Maori settlement, Ngati Toa leader Te Rauparaha composes the famous chant "Ka Mate", also known as the haka, after evading enemy capture by hiding in a kumara pit.