Jack of Shadows, or Shadowjack, is a wizard and rogue, the best thief of his age. His world doesn't rotate. Instead, the light side is ruled by science and the dark side by magic. Daysiders have souls, Darksiders are eternally reborn in the Dung Pits of Glyve. Jack gets decapitated in the opening chapter and seeks revenge upon waking in the aforementioned Dung Pits. On the way to his goal, he gets imprisioned by an old enemy, spends time as a professor at a university on the Dayside, and finds Kolwria, the Key That Was Lost. Once he gets his revenge, a whole slew of other issues pop up.
I found Jack of Shadows to be a very original work. Not a trace of the usual fantasy cliches. Philosophical questions like what it means to have a soul are raised. Jack reminded me of a magical version of the Rowan Atkinson Blackadder character. The ending is open for the reader to interpret.