The series takes place in an alternate universe called "Bushworld", where the sinking of the Titanic never happened, indirectly resulting in the United States being destroyed (except Hollywood, which became an island), Australia becoming the world's superpower, and Nicole Kidman becoming its Queen.
The story follows Kevin Williams, an average middle-aged family man who decides to serve justice to the town of Dapto as the incredibly average superhero Koala Man. Possessing no powers and a simple costume, which is apparently enough to hide his secret identity, Kevin encounters various evildoers who wish to do harm to his town.
Kevin is joined by his family, who put up with his misadventures, including his down-to-earth wife, Vicky, and his 14-year-old twin children, a popularity-obsessed daughter, Alison, and a nerdy son, Liam, who secretly possesses psychic powers.
