Step one: take an Agatha Christie novel
Step two: mix in a bit of One Flew Over the Cuckoo's Nest
Step three: add a little bit of sexual innuendo
Step four: add very distinct and creepy staging
Step five: add religion
Final Step: add horses and...
you've got Equus- a chilling mystery about a lunatic who blinds horses because of...well, now that would be telling the ending of the mystery, wouldn't it!
A must read for anybody mature enough to read it (13+ probably)
Along Dysart's (the psychiatrist who must discover why Alan has committed such a horrible crime) and the reader's journey through Alan's tortured life and mind, the reader comes to partially understand and all but accept Alan's deed as a man's faith betraying him. Dysart, paralelling Alan in the 'normal' world, experiences that loss of worship in a far different, yet equally devastating manner.
I suggest seeing the play performed if at all possible. Seeing Equus live-action truly brings it's horrific brilliance to life.