At a word from critic Ridley Groendal, plays closed overnight. Concert halls went silent. Books gathered dust on bookstore shelves. Thus, many sought revenge. But four were close enough to exact it. The playwright. The violinist. The author. The actress. All with a dark, longtime link to the victim. And to Father Koesler, who'd known Groendal since their school days. Who pulled the curtain down on Ridley? All Father Koesler has to go on are four incriminating letters -- and one burning question