... In 2000, Hugh Hefner and the Playboy empire already seemed like a toothless relic. Yet as Madison writes in her new book, “Down the Rabbit Hole: Curious Adventures and Cautionary Tales of a Former Playboy Bunny” (Dey Street), life behind the mansion walls was darker than she could have imagined.... Then Hef approached her, bent over and opening one hand to reveal a bunch of pills nestled in an old tissue. “Would you like a Quaalude?” he asked. Madison was mortified. “No thanks,” she said. “I don’t do drugs.” “Okay, that’s good,” Hef said. “Usually I don’t approve of...