On arrival in Glasgow she is met by Detective Inspector Dorian Grey (yeah, THE Dorian Grey in all his Victorian finery) and he introduces her to Caledonia Interpol, the equivalent of the Faerie Police. They need her help as both a Police Officer and as something of an expert in Scottish Folklore. There is a serial killer murdering Faeries and they believe it is a human.
Caledonia Interpol is full of creatures from Scottish Myth and Folklore but don't be put off by the mention of Faeries - these are certainly not Tinkerbell and co.
The Glasgow of 'Caledonia' is the gritty, dark underside, the seedy bars, the characters a mix of the fantastical and the local 'neds' but the mix works well. Leah fits into the team fairly quickly but still has moments when it is obvious she is slightly blown away by meeting what she thought were just the stuff of stories.
So, in short - a police procedural with Faeries and Monsters but when you get into it, it is a lot more than that. This is a story that draws you in, that leaves you wanting more* and that makes you want to believe. There is a quote on the front that "Fans of Neil Gaiman, Gail Carriger or Nicole Peelerwill want to take notice...." and, while I am not familiar with the works of Carriger or Peeler, I would certainly compare it favourably to Gaiman's 'Neverwhere'.
* Caledonia is also an online series, links below