“Blue Bloods,” Book #4.5. Hyperion. 2010. 227 pp.
This was the first “place holder” book in the series, with a “behind-the-scenes” look at various aspects of Blue Blood society. De la Cruz uses Repository files to give the back story behind each of the main characters in the previously released books, while including a few “untold” stories straight from the mouths of Jack, Kingsley, Dillon and Schuyler. It ends with a “Glossary” of important Blue Blood terms and people.
“Keys to the Repository” is dry and not very interesting, so there’s no need to interrupt your reading of the regular series with it. I’m sorry I didn’t skip it and go right to book #7 in the series.