There are references in this book to events which happened in Touch & Geaux, Shock & Awe, and Ball & Chain (which should properly be read in that order before you get to Cross & Crown, if you're the sort obsessed with reading things in order. You can read this without having read Ball & Chain, but you won't understand some minor references to Emma Grady or Nick's surgery or Nick's issues with Ty Grady if you haven't.) 
 I really like the Julian Cross-overs in these series because Julian (from Warrior's Cross) is so much fun, but more than anything, I love the banter of the characters. 
 This one has a little bit of "National Treasure" aspect to it (and makes fun of itself by referencing it). Kelly and Nick grow in their appreciation of one another. And I loved the use of the Irish mob in this story. 
 So, another great story. Can't wait for #3. =)