It begins with Scott Lang spent time in prison. After his release,He went to see his daughter,Cassie unannounced and is chastised by his former wife for not providing child support.
That Night,Lang breaks into Hank Pym's house and steals his Ant-Man suit. Scott begun trying it out and accidentally shrink himself. He was later contacted by Hank,who wanted Scott to steal the suit. He wanted to join him & Janet to face Nathan Garret,also called Black,& Chen Lu,also called Radioactive Man.
During his training as Ant-Man with help of Bill Foster,who had two suits,Scott met Pym's daughter,Nadia. Hank reveals that he & his former lover,Maria broke up before Nadia is born. After She was killed during the invasion caused by Loki,Pym takes Nadia in. After Scott finished training,They soon learned that Black Knight & Radioactive Man are preparing to launch a Nuclear Missle and it could destroy the city.
Hank dons Bill's Giant-Man suit and he dons his Goliath suit. The four confronts the villains as the missle prepares to launch. Giant-Man helped Ant-Man on the missle while Wasp fights with Radioactive Man and defeats him. Goliath fights with Black Knight and kills him. Ant-Man successfully shrinks the missle and made it hit the water. Radioactive Man is later arrested. Hank tells Scott about recruiting the Avengers,which he accepts.