SOLVED. Murder mystery with the word DARK in the title, female detective. Someone in a cage of knives or blades has to crawl out. [s]

[Xochitl]

I read this book in 2015 or 2016, I cant remember the title or author. I recall the word Dark being in the title. it was about a serial killer, main character was a female detective who was assigned a male partner at some point. I believe it took place Seattle or the pacific northwest somewhere. The investigation gets personal some how. I think the killer takes someone she cares about. The thing that I remember most is that towards the end someone(i think the male partner) in put in like a cage of knives or blades of some kind and has to crawl out, getting all cut up to save someone. Main characters name possibly starts with R?

[Tab]

What location did the story take place?
Part of a series?
Anything about the cover?

[Xochitl]

In Seattle I believe, and I think it was the first in what was gonna be a series. The secne with the cage is in the woods and I think he's crawling out trying to hit this button that will stop the water filling up a tank with someone in it?

[Xochitl]

I think the cover was brown and black with just the title on it nothing that stood out

[Ayshe]

The Gift of Darkness maybe?

[Xochitl]

You are a goddess! Thats the one thank you so much