For some well-heeled denizens of the U.E.S., Tiffany & Co. might as well be a physiological necessity. Author James Patterson understands this. In his new novel, "Sundays at Tiffany's," a powerful Broadway producer makes time for her daughter, Jane, with a weekly trip to the iconic store. Oh, yes, and her imaginary friend comes along for the ride. The childhood memory becomes a source of comfort. Later on, when a grown-up Jane returns for a retail therapy session, she also reunites with her made-up mate—except now he's real. "It's the kind of high-concept stuff that gets turned into movies," Patterson explained at his book party last night at Tiffany's, though he didn't know whether "Sundays" would be optioned. Does Patterson have a personal equivalent to the jewelry store? "Niketown?" he replied. "I'm not really a possession kind of person, honestly, but my wife loves Tiffany's."