A grieving optometrist is blind to the family drama and psychological deterioration playing out before his very eyes. Today author of "Mercury," Margo Livesey takes us inside a marriage broken by secrets and obsession and tells why she chose a magnificent horse to set off a chain reaction of deceit and crime. In Bookmarks, Mary Ann Gwinn gives us a reading list full of unbridled obsession: five books about horses and the people who love them.