I will add a caveat that I am a friend of the author, and I got an early peek at this, but I also wouldn't BS you - I had a lot of fun reading this short. 
 I like shorts, and I've read my share of "prequel shorts" - the little intros to give you a taste of a new series. This is one of my favorites because I am an action-junkie and there is A LOT of action packed in here. You also get a good picture of the dynamics of the world Jessica lives in, and a good intro to the supporting characters.