The Fallen by T. Jefferson Parker
Detective novels are my go to books when I can't find anything I like at the library. Or when I'm too lazy to actually look.
I like T. Jefferson Parker-his books are usually set in San Diego County, where I lived for quite a while, so they bring back memories, both good and bad.
Anyway, this is the story of a cop who, after a fall(more specifically, a throw) from a 6 story window, discovers he now has synethesia-his version lets him see emotions as colored shapes-when someone is lying, he sees black squares tumbling out of their mouths, envy is green triangles, whatever. Someone gets murdered, and he has to solve it.
Like I say, not a bad read!