Following the events of Avengers: Endgame, a high school student and superhero goes on a much-needed vacation with his classmates to Europe. Struggling with the legacy of a fallen hero and the responsibilities of his double life, he plans to leave his crime-fighting duties behind temporarily to focus on being a teenager. During his trip, he hopes to express his growing feelings for a fellow classmate and enjoy the sights. However, his attempt to lead a normal life is disrupted when he is approached by a government agent who requests his help in combating a new threat.

The emergence of mysterious elemental creatures wreaking havoc across the continent compels the young hero to step up and tackle the challenge. He is introduced to a new ally, a seemingly powerful figure who appears to have the capability to fight these beings. The two team up, and as they travel from city to city saving the populace from destruction, the young superhero learns more about what it means to be a hero, the importance of trust and the delicate balance of having a dual identity. As the crisis escalates, he must decide what kind of hero he wants to be and what he is willing to sacrifice for the greater good.