Almost 4 stars. 
 The time-travel aspect is what had drawn me to this book in the first place. I just like that sort of thing. There are a few other time books that I can recommend to those interested. Crime novels? Yes, I often like those too. Combining these two ideas into one story was a win-win. 
 I wish this would have ended as it started for me, in terms of its raw uniqueness and how the plot initially grabbed me. That plot was exciting and different: a twisted killer finds the key to step out the door of 1931 into any time period until 1993. There are certain girls who "shine" for Harper, and Kirby, the main character, is one of them. For some reason, there is a limit to that time shift (to know, you must read it). Shit, that premise sounded good to me, and it readily lived up to my expectations, until things kind of went flat. I can't reason why, specifically, the story fell short of those early hopes, except to say that each of the criminal's later time jumps became a bit less interesting, and the main character's later development (who I still really like) had lost some of the edge that had defined her early on. 
 Still, I will recommend this book to scif-fi and crime fans that are looking for something a little different from the same blase. It's hardly a waste of time, and I feel that many will appreciate it. It's smart, without being overly complicated, and it reads well because the writing is good. Bonus for Chicagoans (where this plotline is based).