This was very good. It start slow with character devlopment in a more literary fiction way. After about 100 pages the thriller part starts and you are hooked. This is a true page-turner. 

This story is absolutely horriffic, gruesome, and dark. Definitely not for the faint of heart! I was triggered multiple times and I am not easily triggered in the wsy this book triggered me. So, this is definitely a book you should consider carefully, and you need to be in the right mindset to read this.

The fact that you don't know who to trust gives the story another scary element. 
I loved reading about the sister dynamic. 

The story is told from the POVs of two sisters, and the diary from their dad. The diary was not super interesting to me.
The ending wasn't my favorite. It felt a bit sloppily finished. But for the rest this was an amazing thriller and I would recommend it to anyone who can handle dark thrillers.