The second tie-in novel for Supernatural sees the Winchesters leaving the bustle of New York behind them and heading to a remote town in Arizona. This novel follows on directly from the events described in 'Supernatural: Nevermore' but apart from a brief mention in the introductory chapter of a character from the earlier novel, the two books aren't otherwise connected.
Without giving away the plot, Sam and Dean are warned that the next bout of savage murders that takes place in a small town in Arizona every forty years is imminent, so the Winchester brothers head over there intending to deal with whatever is responsible. They arrive in time for the first death, and as the body count grows day by day, Sam and Dean are left trying to figure out who or what is doing the killing and how to stop it.
Overall I enjoyed this novel. It was an easy read with a plot that moved along at a good pace. My one criticism would be that after all the build up, the ending seemed rushed and a little abrupt. The characterisation of Sam and Dean was, for the most part, true to how they appear in the series. One of the strengths of the book was the dialogue, especially that between the brothers, which was convincing enough in most places that it didn't take much imagination to hear the actors' voices speaking the words. A bonus on the characterisation front was a couple of brief flashbacks to the brothers' childhood that filled in a bit of background. Supporting characters, even those that would soon contribute to the body count, were described enough that they were more than just ciphers.
As far as tv tie-in novels go, I'd categorise this as one of the better ones.