I recommend Blood Promise. 
 ***** 
 REVELATIONS. 
 Blood Promise started out great, got boring in the middle, then slamdunkenly surprising in the end (well almost, there's this one part that i'm pretty sure is predictable). I have mixed feelings on this one, but the wrap-up made all the difference for it to garner 4 stars. Really, Richelle Mead, i thought you're running out of material and yet this fourth book shoots to a whole new level of awesome. 
 Rose went to Russia (or was it Siberia already?) to look for Dmitri's hometown in hopes of finding him there. She met Sydney (the alchemist), Abe (the mobster), and eventually Dmitri's family (the Belikovs). Rose is on the verge of a being a lost cause: she misses Lissa (which is still a weakling, ugh), she still can't find Dmitri, and she's haunted by Dmitri's memories. I felt bad for her, but she's strong. But when she became that one thing she fears the most (after her fear of turning Strigoi), I started to condemn her. She lost her dhampir skills and abilities which took up a lot of time. Sigh. But she bumped her head, retrieved her senses (thank God!) and got better in the end. I love the last part of the book, nearing the end, where she doesn't give up despite the odds being stacked against her. Wow, that's resilience. 
 There are a lot of new characters here, and the expansion was workable on Rose's story that is still evolving to new adventures. 
 Blood Promise is a startling read. When you lose someone you love, do you try your best to move on? or do you pursue any idea, no matter how crazy it is, and do it just to bring them back? How about you and Rose have a talk, because she's contemplating this as well, since her love for Dmitri certainly knows no bounds.