Mark Grayson is teenage superhero Invincible. He was a normal high school senior with a normal part-time job and otherwise normal life, except his father Nolan is the superhero Omni-Man, the most powerful superhero on the planet. At the age of 17, Mark begins to display superpowers, which come from his father being a member of the Viltrumite race, who, according to Nolan, pioneer the galaxy on a mission of benevolence and enlightenment.
As Invincible, Mark begins working as a superhero, with his father acting as his mentor, and meeting other heroes. Mark worked occasionally with a superhero team called the Teen Team (consisting of Robot, Rex Plode, Dupli-Kate and Atom Eve), from there discovering that his Physics teacher has been turning his students into human bombs. He stops his teacher with the help of the heroine, Atom Eve. He also foils a plan to make an army of robots, created by the Mauler Twins. Meanwhile Omni-Man is kidnapped by aliens, taken to another dimension, but returns after what seems to be only a few days, but was actually eight months to him.