Help for the Haunted

I loved 90% of this book. LOVED IT. I couldn't help thinking of the movie The Conjuring as I read it. Sylvie and Rose are daughters of the (almost) famous Masons, a married couple who work as a team to help people who are “haunted”. In their travels they have collected a few items of disrepute, including a spooky rag doll that may or may not be evil.
This is the story of Sylvie who is navigating a time after her parent's murder and trying to pull herself together enough to confront the man she saw the night her parents died. This is also the story of the family before the murder, and the people in Sylvie's life that have either hurt or helped her parents on their mission to explore the paranormal.
Most of this novel had me flipping pages so fast, my fingers burned.
I wont discuss the ending, because it is a big reveal. I will admit I didn't see it coming, and when it got there- it didn't quite gel for me. It felt out of place, and what happens to the characters after that seemed a bit far-fetched.
I would love to see a sequel. Maybe Sylvie striking out on her own? Or with Derek?