"In March of 1909, Mark Twain cheerfully blessed the wedding of his private secretary, Isabel V. Lyon, and his business manager, Ralph Ashcroft. One month later, he fired both. He proceeded to write a ferocious 429-page rant about the pair, calling Isabel "a liar, a forger, a thief, a hypocrite, a drunkard, a sneak, a humbug, a traitor, a conspirator, a filthy-minded and salacious slut pining for seduction." Twain and his daughter, Clara Clemens,...