Ghost Night book 3. Spoilers ahead for the earlier books and for the earlier two series, too.
Caina and all the rest, on their road to deliver the evil and magical ring to safe keeping, come to a city. Where not only are there events that will affect the empire, but also Caina's aunt, plotting.
It involves an evil younger brother, the use of make-up, sneaking about sewers, crossing a ford, an assassin admitting that his target might have escape, and more.