I'm not a huge mystery book person, mostly because it seems that many of them tell the same story with a slight twist. This is a very unique story line, well-written, intelligent, and it kept me interested. Here's a bit from another review:
From the author of a string of fine novels comes a very intelligent, turn-the-pages-as-fast-as-you-can thriller that pits a psychoanalyst against a brilliant - and deeply disturbed - villain. The premise: the villain, who calls himself Rumplestiltskin, has given Dr. Frederick Starks two weeks in which to guess his identity. If he can't guess it, Rumplestiltskin will begin killing off people close to Dr. Starks, and he'll keep killing, unless Starks kills himself.
I mean, that's one killer of a premise: find out who the bad guy is, or you'll be forced to kill yourself. And Rumplestiltskin doesn't exactly make it easy for the good doctor: a few tantalizing clues, little verses that could mean nothing, or anything, but that's it.