Gatekeeper follows Rachel, a daemon collector who lives in a dimension that, as the synopsis states, is just adjacent to ours and known as the Arcana. This alternate dimension basically helps to keep things running smoothly in our dimension, which is where Rachel comes in by collecting and helping find daemons who need to be rehabilitated become the daemon they were meant ot be. Now, these daemons probably aren't quite the type you're thinking of, but rather daemons that sort of live in the background of our everyday lives and plants seeds of ideas in the minds of humans, such as ideas of riot or discord that influences how people may react in different situations. A daemon is considered 'defective' if it either isn't doing that or is getting a bit out of control. I really love concepts like these and I thought that Levy did a great job developing this multi-dimensional setting.
Our protagonist, Rachel, was someone I enjoyed getting to know and I found unexpectedly charismatic. I found her snow globe-like living situation really interesting and I enjoyed seeing how she managed to balance straddling two dimensions, as it's not necessarily something that is overly common. She's not necessarily the warmest or friendliest of people, but she's good at what she does, she's loyal, and she doesn't give up easily. In Gatekeeper, she gets stuck with a rather unfortunate assignment (due to her own oversleeping) and despite her exceedingly strong desire not to follow through with her assignment, she does it anyway and puts a strong amount of effort into getting everything done right, which I really appreciated about her character.
The daemons themselves were particularly fun to learn about and I thought all of the different varieties of daemons that exist were a really unique idea. It was interesting to hear about how the daemons interact with out dimension and the process that occurs when they are declared 'defective,' which we get to see a few examples of in Gatekeeper when Rachel is tasked to find and bring them in.
I also found Levy's writing style engaging and easy to follow. There was something pleasingly straightforward about the narrative--it was simple without being boring, yet still somehow full of details and depth. I think it is because of the writing style that I was hooked almost immediately upon starting the book, and I genuinely enjoyed the entire book with the same level of intrigue. I don't htink I ever once found myself losing interest and I credit that completely to not only the interesting plot and world-building, but to Levy's skill at pacing and crafting a captivating narrative style.
Overall, I've given Gatekeeper 4.25 stars! If you're looking for a quick fantasy with a really interesting and fun premise and worldbuilding, then I'd encourage you to pick up Gatekeeper!