These are the books by Kate Thompson that are reviewed on this site:
Rilka sets out on a quest to catch a beguiler and to understand its nature. And in doing so she learns a lot about her own nature too.
The New Policeman
One problem. Two people trying to solve it. Faery and Ploddy. Course, you'll have to believe in faeries to get on with this one.
A tale of highway robbery, but not necessarily the obvious kind.