The film is the third film in the "Ant-Man" series and also the opening work of the fifth phase of the Marvel Cinematic Universe. The story takes place after "Avengers 4: Endgame". "Ant-Man" Scott Lang (Paul Rudd) and "The Wasp" Hope van Dyne (Evangeline Lilly) have become heroes who save the world. Dr. Pym and Janet, who has returned after a long absence, are also enjoying a peaceful semi-retired life. However, due to an accident, they and Scott's daughter Cathy (Kathryn Newton) stray into the quantum realm. In this dangerous and unknown world, they encounter the strongest villain in the Marvel Cinematic Universe, Kang the Conqueror (Jonathan Majors), and begin an adventure beyond their imagination.