The Gaudí key

As the Grand Master of an ancient religious brotherhood nears death, he chooses to entrust to Antonio Gaudi a sacred object whose existence has been a guarded secret since the early Christian era. The great architect protects the artefact by hiding it where he believes it might never be discovered... A century later in Barcelona, the granddaughter of an apprentice to whom Gaudi passed along his secret is charged with finding it. With the help of her mathematician boyfriend, Maria unravels the clues Gaudi placed in his work. Their goal, she believes, is the whereabouts and meaning of a sacred relic. As their quest leads them to the outer limits of good and evil, however, both realize that far more is at stake.