Picking up a few months after the Avengers battle the Satari, deep in the heart of Africa, T'Challa, the Prince of Wakanda, returns from the outside world to learn the kingdom is being attacked by Herr Kleiser, the alien shape-shifter who battled Captain America during World War II is still alive. T'karak, T' Challa's father dons the garb of the Black Panther and the two battle Kleiser and his Santari forces in combat. The battle doesn't go well and T'Challa is almost killed by Kleiser until T'kara uses the full powers of the Black Panther and saves his son but loses his life in the process. T'Challa is named the new King of Wakanda and learns that the Santari are seeking Wakanda's store of vibranium, which they have kept in secret from many years after a Santari batlte ship crashed langed in Wakanda decades before, the metal the Santari use the metal to manufacture their ships and weapons. After becoming King and assuming the alias of the Black Panther, T' Challa seeks the aid of Captain America. General Nick Fury of SHIELD and orders the Ultimate Avengers to assemble, with the exception of Thor (who is unavailable and having it out with his father, Odin) and the Hulk (his alter ego Bruce Banner is being kept under surveillance and tortured by his captives ).
Meanwhile, Hank Pym and Janet are having problems as Hank continues to push his powers to his limits and keeps blaming Jan for his failures for his experiments and lack of being a better super hero. The Avengers head to Wakanda after learning that Herr Kleiser is the Santari's own super soldier and probably can't be killed. During a misunderstanding with the Wakanda Ruling Council in which the Ultimate Avengers are attacked by the Wakandan soldiers, the Wasp being injured and Captain America's shield being stolen, the team rally and together with Thor who has decided to stand by his mortal friends despite his father's wishes and comes to battle the alien Santari. Back in New York, Banner deduces that gamma radiation will weaken vibranium after seeing his earlier attack on the alien warloards and sends Betty to Wakanda with a gamma-ray projector. However, Banner's captives continue to torture him until the Santari arrive and try to kill Banner, who soon "hulks out" and attacks his attackers and leaves the base. The Wakanda Council continues to igonore the Avengers help using the crashed Santari technology to keep their forces back but Kleiser soon discovers the truth and they deactivate the ship, causing their defenses to drop. In doing so, the Santari Base Ship approaches the planet and encases the country in an energy shield while Captain America and the Black Panther battle Kleiser. Below in Wakanda with the gamma ray being used by the Avengersthe Santari are weakened, and Iron Man (using his War Machine Armor) and Giant Man(Henry Pym) manage to destroy the core of an attacking Santari vessel. Giant-Man, however, is fatally injured and dies. Captain America and the Black Panther who are unable to truly kill Kleiser instead bury him in liquid vibranium, leaving him trapped and unable to regnerate and bury him deep within the palace, never to be heard from again. Later, the team departs with the thanks of the Black Panther, and on returning learn that Banner has become the Hulk and escape. They later hold a funeral for Hank Pym and the Black Widow and Captain America finally kiss and begin a relationship together.