Plunging ratings. Tense negotiations. A bewildered, increasingly outraged Conan O’Brien and an anxiously pragmatic Jay Leno. In this excerpt from his new book, Bill Carter unfurls the behind-the-scenes story of late night’s explosive 2010 showdown. (“What does Jay have on you?” Conan asked, his voice still low, his tone still even. “What does this guy have on you people? What the hell is it about Jay?”)