As the Avengers find a way to return Iron Man to their reality without bringing Ultron along, they managed to prevent Ghost from stealing Stark Industries technology at the Stark Expo. After swiping the prototype Arc Reactor, Leader head to the Wakandan Consulate to steal the Vibranium there with his army of Humanoids. When a guilt-ridden Thor helps Black Panther take down Leader when the Avengers arrive, Leader summons his new incarnation of the Cabal (consisting of Arnim Zola, Enchantress, Executioner, and Kang the Conqueror) to fight the Avengers while taking advantage of Iron Man not being there.
"Marvel's Avengers Assemble" reunites the most popular super hero team - Iron Man, Hulk, Captain America, Thor, Hawkeye and Black Widow, along with newcomer Falcon, marking the first time in animation history this distinct team of heroes will join forces.
Led by Iron Man, the heroes train and live together in their new headquarters in Avengers Tower. The planet's most dangerous villains don't stand a chance when the Avengers assemble - whether they are stopping Dr. Doom from conquering Asgard, Attuma driving the Atlantean Army into New York City or Dracula unleashing vampire hordes, the Avengers must work together to succeed.