Even as he grows stronger and closer to discovering the secret of his identity, Arthur must face further dangers and conflicts as he struggles to attain the Sixth Key from the powerful Saturday.

When Arthur is drafted into the Glorious Army of the Architect by Sir Thursday, he must survive basic training, avoid getting posted to the Front, and figure out how to free Part Four of the Will, while Leaf tries to banish Arthur's doppleganger on Earth.

Young Arthur Penhaligon must weigh an offer from Lady Friday that is either a cunning trap for the Rightful Heir or a golden opportunity that he must seize.