Arthur Penhaligon, star of Garth Nix's Mister Monday, thinks he's a normal 7th grader who has enough problems to deal with, like starting a brand new school and controlling his asthma. After the first day of school, though, his life gets a lot weirder. During a serious asthma attack, while he's gasping for breath on the ground, he sees a strange man in a wheelchair appear in blinding light with an attendant. He thrusts a "blade" into Arthur's hands and mutters some strange things about a Will, the Key, and suitable Heir. Although it makes no sense to him at the time, Arthur has just been given an instrument of power called the Key and named the Heir to the Will by Mister Monday. Arthur's life will never be the same.