Carlos Ruiz Zafon's haunting gothic mystery, which has long been a cult classic in Spain and is now an international bestseller.   "We all have a secret buried under lock and key in the attic of our soul. This is mine."   Fifteen-year-old Oscar Drai meets the strange Marina while he's out exploring an old quarter of Barcelona. She leads Oscar to a cemetery, where they watch a macabre ritual that occurs on the last Sunday of each month. At exactly 10 o'clock in the morning, a woman shrouded in a black velvet cloak descends from her carriage to place a single rose on an unmarked grave.   When Oscar and Marina decide to follow her, they begin a journey that transports them to a forgotten postwar Barcelona—a world of aristocrats and actresses, inventors and tycoons—and reveals a dark secret that lies waiting in the mysterious labyrinth beneath the city streets.