Meanwhile, William Reticulata-Iris is dealing with the ramifications of his deadly actions and also the truth that Cathy has been hiding a lot from him, as he recently discovered her cell phone, secret bank account and on and on, from her time in Mundanus. Can these two ever trust one another? They'll have to if they plan on making their reign as Duke and Duchess of Londinium a success, something that Lord Iris sternly demands.
Things aren't really rosy for Max the Arbiter, his animated gargoyle, and Ekstrand, the Sorcerer of Wessex either. It seems there's a battle royale going on and the Sorcerers of Albion are the prime targets. Ekstrand is convinced it's Rupert, the Sorcerer or Mercia, and as the pair fight it out trying to destroy one another, Albion could soon find itself Sorcerer-less.
Rupert is quite different than any other Sorcerer, in that he swears like a sailor, dresses like a slacker mundane, and revels in modernity, unlike all of the other Sorcerers so clearly stuck in the past. He takes an interest in Margritte, widow of former (for an hour) Duke of Londinium, Bartholomew Semper-Augustus-Tulipa, and agrees to help her exact revenge upon William, as her plot to undermine William socially finds itself faltering. However, the situation escalates dramatically and, before you know it, another Iris has claimed a large city and William must simply watch in astonishment as things unfold.
On the upside, William and Cathy have finally found love with each other, and as Cathy continues to research the intricacies of Society and discovers the horrific secret of what really happens to those who speak out, she is ever more determined to break the chains that bind the women of Society in the Nether. William is determined to help her on her mission, but does he truly know what she is capable of and can he withstand the pressure from Lord Iris once she sets things in motion?
Last, but certainly not least, is Sam, who is still reeling from Leanne's death. Strangely, her boss, Mr. Ferran, has taken Sam under his wing during this difficult time and Sam is grieving at Ferran's luxurious estate, whiling the days away learning blacksmithing, of all things. He discovers a letter Leanne left for him, along with boxes and boxes of material she discovered while working at CoFerrum and it seems she was up to something and it wasn't just climbing the corporate ladder. While it gives Sam a measure of comfort that she didn't just abandon him because she was outgrowing him, his heart aches that he has lost her and he is determined to carry on her mission. Too bad that Mr. Ferran has other plans for Sam and they are most shocking and will forever alter the course of his life.
All is Fair: The Split Worlds - Book Three ends with Cathy about to address the Court in Londinium and we can only hold our breath and wait to see which great tree she shakes first in Society. Although she has discovered some allies, she continues to make more and more powerful enemies; and you might remember way back in Between Two Thorns, the first book, her final wish granted by Lord Poppy was that she reach her true potential, and as a result, all of Albion should be quaking in their boots as she heads their way.