Need Help Finding A Story

Howdy!

So, as title says, I need help finding a story. Now, beware, this post will contain spoilers. While I can't remember the name of the story, I do remember the general plot (you, in the back row; quit yer sniggering).

So, without further ado:

- Twilight is a detective investigating a bunch of murders, with Spike her assistant.
- RD is a sniper, killing people for money to help Applejack keep her farm.
- In a flashback, RD, Fluttershy and Big Mac were conscripted in a war with Zebra's. Fluttershy...yeah :(
- Spike also gets shot, but survives thanks to his scales.

That's all I can remember, sowwie.

I't greatly appreciate if someone could tell me the name of the story. It was the first fic I read, and It's been driving me nuts.