Content Warning: This section of the guide includes discussion of self-injury, sexual assault, torture, and homicide. 

Twenty-one-year-old Kell Maresh has the power to travel between worlds. There are four parallel worlds—the magicless world of Grey London, the lost realm of Black London, the desolate world of White London, and the thriving empire of Red London. In October 1819, Kell journeys from his home in Red London to Grey London to bring a message from his queen to King George III. The letter from Queen Emira bears the emblem of the red throne, “a chalice with a rising sun” (14), and is courteous but brief. Kell consoles the ailing king by improvising a longer message. Kell is forbidden to leave anything from his world in Grey London except for the queen’s letters. However, when Kell first met George III, the king requested a coin from Red London as proof of the boy’s story. Whenever Kell pays him a visit, George III claims that the scent of magic has worn off his coin and insists on trading it for another. Although Kell always protests that this is against the rules, he indulges the elderly royal each time.

With his message to the king delivered, Kell prepares to visit George III’s son, the Prince Regent, at St.