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. Four of the seven trustees have been defeated and their Keys taken, but for Arthur Penhaligon, the week is still getting worse. His friends have been captured by the Piper, and the New Nithling army still controls most of the Great Maze. Meanwhile, Superior Saturday is causing trouble wherever she can, including turning off all the elevators in the House and blocking the Front Door to prevent escape. Amidst all this trouble, Arthur must weigh an offer from Lady Friday that is either a cunning trap for the Rightful Heir, or a golden opportunity he must seize before Superior Saturday or the Piper beats him to it. The race to find the secret of the Middle House is on - and Arthur is in the thick of it.