Dark Assassin by Joseph Delaney
Dark Assassin is the third book in the Starblade Chronicles by Joseph Delaney. Set in the world following Tom Ward who is a Spook, hunting ghosts, ghouls, witches and other creatures, alongside Jenny, his apprentice and the worlds first female Spook. I can't give a synopsis of this individual book without spoiling the two previous books, but trust me, you need to read this series. If you love kick-ass fantasy stories with ace main characters, this is a perfect series and you don't need to have read the previous Delaney series set in the same world (with Tom as a main character in other series) to read this series. Highly, highly recommend reading this series and to be entirely honest, the third book is my favourite of the three.