I started reading this book with high expectations which unfortunately weren't quite meet! 
The Hollow Sisters disappeared for a month 10 years ago and where never quite the same, their appearance changed and they can't quite remember what happened. When the oldest sister go missing the other two have to find her.

whist looking for their missing Sister Grey Vivi and Iris start to unravel what happened to them 10 years ago! They discover they went to the halfway place, a place full if death and decay, where the dead with unfinished business are stuck. A mysterious man kidnaps Grey and Vivi and takes them back to the halfway and Iris follows to save them. Whilst there Iris learns they are not who they think and they are changelings, and Grey enticed the Hollow sisters into the halfway so they could take there place.

I found it a bit slow going and I guessed the majority the twists at the end which kind of spoiled it for me and the ones I didn't guess didn't have me gasping or shocked.