The son of the King, T'challa, return to get the throne. They remove his ex-lover, Nakia, from an undercover assignment so she can attend the coronation with his mom and super smart sis. At the coronation, the leader of the Jabari tribe, Okoye, that is not united as Wakanda, challenge him to fight. They lost and T'challa showed him mercy by not killing that leader.
Klaw and his accomplice, Erik, want to steal the Wakanda artefact from UK Museum. Okoye, T'challa and his lover, Nakia, go to stop the sale between Klaw and Everett K Ross. They didn't pursue Klaw and brought Ross back to Wakanda so that Shuri, T'challa sister can heal him with that Vibranium technology.
Killmonger challenges T'challa to combat and T'challa lost. Killmonger flings him to his death. Killmonger ingests the heart-shaped herb and gets superhuman powers. He orders the rest to be destroyed but not before Nakia takes one.
Mother, sister, gf and Ross flee to Jabari tribe and they find T'challa there saved by them as gratitude for not killing their leader. T'challa eats the last herb and fights killmonger. He dies and doesn't want to be healed so that he remains free.
T'challa sets up an outreach Centre run by Shuri and gf in memory of his uncle. He appeared in the UN to show Wakanda's true nature to the world and helped heal Bucky.