I was excited to see Keys to the Repository on NetGalley because I have been looking everywhere for this book, and began wondering if I was going to have to order it from one of my retailers instead just to get it. Haha. For some reason, it's really hard to come by any of the books for The Blue Bloods series in my area. Odd. I absolutely adore this series. A friend of mine recommended it to me a couple of years ago and I was hooked from the beginning. Unfortunately, I don't get each installment right at release time always like I want, and usually wait until paperback release. The last year I've been reading and reviewing so much on other works, that I've got a bit behind on this one and I missed it. Keys to the Repository also helped me realize just how much I really missed the characters and story. I can't wait to start my copy of Misguided Angel soon and get back on track again.This is not an installment to the series. It's not really necessary for someone to read it if they're reading the series, but it does provide a lot of extra information and backstories on the characters and events as well. I found it to be a great and interesting companion novel-- and if you're like me, a bit behind and needing to catch up, this will certainly help jog the memory on everything between books 1-4. An enjoyable, quick read!3.5 stars!