Darker than your usual stuff. I wonder what influenced this.
I like your art, it's cute, cartoony and simplistic. Though your animation might need some work. Now your animation is good here and there. But you might need to work a bit more on the movements like with the arms and heads. I say this because with head movements I noticed the character's head all of a sudden got smaller than it originally was. Consistency is a must. Also, the hands and feet of the humans looked kinda weird at some point. Might need to work on the body. Now anatomy study might not really involve cartooning much but it does help improve the sizes of certain body parts like the hands, fingers, legs, etc. I mean most cartoonists and animators study the anatomy and how it moves before developing their style even further. I should know because I'm practicing my animation and anatomy myself here and there.
As for the plot of the flash, it felt like just random killing and didn't have much of a point to it. Sure, we can kind of interpret the situation here. She's a fox that's basically going after hunters who kill foxes for fur. But I think a bit more can be added to this. More of a story and maybe make it a bit more dramatic. I mean, I like the idea as it's a pretty darn good one. But you might need to try to get some help with more than one person to try and help expand the writing a bit more.
As for the music, it was pretty much suitable and I didn't have any problem with it. But the rock musi c might be only good for the intro but more suspenseful music (minus the singing) can also help set the mood. I mean look at many of the disney films and even animated films from Ralph Bakshi, Brad Bird, Pixar, etc. They all have the appropriate music for the appropriate setting. I mean you could try to use some action music BGM and there are some instrumental songs here on Newgrounds that you could use as well. Sorta like what you did for the Bigger Fish to Fly.
Overall, this was decent to watch. I really liked the darker turn for your stuff. Shows that you have quite a variety in your stuff. Keep it up, dude.
PS:- Hope this was helpful, cuz I might not sound all that helpful but I'm trying.