A masterful thriller by the author of the #1 New York Times bestseller The Da Vinci CodeWhen the NSA's invincible code-breaking machine encounters a mysterious code it cannot break, the agency calls its head cryptographer, Susan Fletcher, a brilliant, beautiful mathematician. What she uncovers sends shock waves through the corridors of power. The NSA is being held hostage-not by guns or bombs-but by a code so complex that if released would cripple U.S. intelligence. Caught in an accelerating tempest of secrecy and lies, Fletcher battles to save the agency she believes in. Betrayed on all sides, she finds herself fighting not only for her country but for her life, and in the end, for the life of the man she loves.

Robert Langdon, Harvard Professor of symbology, receives an urgent late-night call while in Paris: the curator of the Louvre has been murdered. Alongside the body is a series of baffling ciphers. Langdon and a gifted French cryptologist, Sophie Neveu, are stunned to find a trail that leads to the works of Da Vinci – and further. The curator, part of a secret society named the Priory of Sion, may have sacrificed his life to keep secret the location of a vastly important religious relic hidden for centuries. It appears that the clandestine Vatican-sanctioned Catholic sect Opus Dei has now made its move. Unless Landon and Neveu can decipher the labyrinthine code and quickly assemble the pieces of the puzzle, the Priory’s secret – and a stunning historical truth – will be lost forever.