Sir Thursday: The Keys to the Kingdom 4

Out-of-this-world magical adventure series for teens from the award-winning, New York Times bestselling author of Sabriel and the Old Kingdom series.
Seven days. Seven keys. One very unlikely hero.
IT'S THURSDAY. Following their adventure on the Border Sea, Arthur and Leaf are set on heading home. But only Leaf can make it through the Front Door. Arthur is blocked because someone - or something - has assumed his identity and is taking over his life. Before Arthur can take action, he is drafted by the strange Sir Thursday and forced to join the Glorious Army of the Architect. While Leaf tries to banish Arthur's double on earth, Arthur must survive his basic training, avoid getting posted to the front, and work out how he can free Part Four of the Will.
Is this a war that Arthur can win... or is his only hope to escape it?

Garth Nix was born in 1963 in Melbourne, Australia. A full-time writer since 2001, he has worked as a literary agent, marketing consultant, book editor, book publicist, book sales representative, bookseller, and as a part-time soldier in the Australian Army Reserve. Garth's books include the award-winning Old Kingdom fantasy novels; the six books of The Seventh Tower sequence; The Keys to the Kingdom series; and with Sean Williams, the Troubletwisters books and Spirit Animals: Blood Ties. He is also the author of Frogkisser! and other novels for younger children.
More than six million copies of Garth's books have been sold around the world and his work has been translated into 40 languages. He lives in Sydney, Australia. Follow Garth on twitter at @garthnix or at www.garthnix.com