Mister Monday by Garth Nix
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.
First, brutal dog-faced men come for him at the school library, attacking the librarian in their attempt to reclaim the Key. Then a drug-resistant influenza appears, sending the town into quarantine and bringing biocontainment units to secure the area. Arthur realizes that the people he cares for are now in danger due to this Key, and he needs to find some answers. Arthur enters the House, another world that contains various areas (more like lands) governed by different leaders (Mister Monday, Grim Tuesday, and so on). He mets the plucky, intrepid Suzy Turquoise Blue, an inkfiller who travels throughout the House and becomes Arthur's guide and companion.
It doesn't take long to start admiring Arthur and cheering for him to prevail against the evil dog-faces and nefarious Mister Monday. Arthur is an unlikely hero, neither particularly strong, physically talented, or intellectually sophisticated. But he has admirable grit, a good amount of ingenuity, and persistent determination. The world of the House can be a pretty confusing place. I worried less about absorbing all of the details and more on enjoying Arthur's adventures.
Visit the book's Web site to meet the main characters and read an excerpt of the book. Mister Monday is the first in the Keys to the Kingdom series, which consists of seven books. Continue reading the series with Grim Tuesday.