Peter and The World follows the adventures of Peter, a nine-year-old boy living in Brookhaven with his large family-seven brothers and two sisters. The story begins with everyday school life, sibling dynamics, and humorous moments, quickly introducing Peter's imaginative world where ordinary days turn extraordinary.

Peter's journey takes him from breaking his arm at school to family pizza nights, roller coaster trips, and the excitement of getting a pet dog. As the story unfolds, Peter and his siblings discover their superhero powers, each with unique abilities like lightning, ice, fire, wind, and Peter himself as "Moon Boy." Together, they form a superhero team, facing challenges such as battling villains like Beyonder and Green Goblin, saving their town, and even rescuing the mayor's cat.

The book blends real-life events-school experiments, birthday parties, family vacations, and moving to a new city-with superhero missions. Peter's leadership and inventiveness shine as he builds costumes, gadgets, and secret hideouts, involving both his brothers and sisters in the action. The family's adventures include cleaning up the ocean, handling snow days, and navigating the ups and downs of sibling relationships.

As the story progresses, Peter's family expands when they foster fourteen new kids, introducing fresh personalities and powers to the superhero crew. The climax brings a twist: Peter meets another "Moon Boy" from a different universe, opening the door to interdimensional adventures and hinting at even greater threats ahead.
The book ends with Peter and his team ready to build a ship to travel between universes, setting the stage for the next installment: Peter and the Different Universes.