Jacob Lev is an alcoholic, almost washed-up LAPD detective who's been relegated to the traffic department. Then an unidentified severed head is found in an abandoned house along with the Hebrew word for "justice". Lev is reassigned to the ensuing murder investigation, apparently because of his Jewish heritage. It soon becomes clear that this isn't a routine murder inquiry but rather a secretive endeavor to be conducted from Jacob's apartment.
As Jacob uncovers clues he discovers that a series of interconnected murders are the work of one or more serial killers. In his pursuit of the killers Jacob travels to Prague where he makes startling discoveries related to his family as well as the crimes. To add to the mystery Jacob has encounters with an exotic beautiful woman and a huge, angry horned beetle - both of which seem to have some connection with what's going on.
A second pseudo-biblical tale alternates with the story of Jacob's investigation. This historical tale - which starts out with Cain and Abel competing for the same woman and evolves into the origin of the golem of Prague - turns out to have links to the current serial murders. Jacob's beloved father Sam, a rabbinical scholar, also seems to have some connection with the historical tale and ancient Prague.
The conglomeration of the modern story and the bible-like story doesn't work well. While the narration of Jacob's murder investigation is mildly engaging the historical tale is slow and - for most of the book - doesn't seem to be going anywhere.
It seems like one or both authors wanted to make use of (what seems to be) a thorough Yeshiva education, injecting a good deal of Jewish philosophy and beliefs into the book. There's too much of this though, and it doesn't fit in with the book's murder inquiry. This type of thing has been been done much better in the "Rabbi Small" mysteries by Harry Kemelman.
In any case, by the end of the book it seemed like an unlikely, disjointed fairy tale about (I think) justice across the ages. Moreover, I didn't care about the crimes, who committed them, or why. I was just glad to be done with the book.
I'm a fan of Jonathan Kellerman and have enjoyed many of his books but this collaboration of the father son team - Jonathan and Jesse Kellerman - is not a success. I don't recommend this book.