Henry and his friend Mr. Fogarty return to the Faerie Realm to help their friends, the royal siblings Pyrgus and Holly Blue, in their continued fight against the treacherous Lord Hairstreak and the evil forces of the Faeries of the Night.

When a terrible plague takes over the faerie realm and causes its inhabitants to age unnaturally quickly, Henry and Blue must find a cure in order to save the realm.

At his father's funeral, Edward Michael "Em" Goverton notices armed men have shown up, and these armed men follow him home. Em has discovered a five-hundred-year-old prophecy by Nostradamus, and these armed men work for men who are connected to that prophecy. With only a stranger named Victor and a family friend named Charlotte as allies, Em embarks on a quest to uncover a conspiracy and stop the end of the world.

Stubborn and feisty Mella, the half-faerie, half-human daughter of Lord Henry and Queen Holly Blue, has the power to determine the fate of both the faerie and "analogue world" when she travels to the country of Haleklind and discovers rebel forces preparing for war.