Dan Brown Book Set- Angels & Demons and Digital Fortress

The 1st book is Digital Fortress. When the National Security Agency’s invincible code-breaking machine encounters a mysterious code it cannot break, the agency calls its head cryptographer, Susan Fletcher, a brilliant and 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 ingeniously complex that if released it would cripple U.S. intelligence.
The 2nd book is Angels & Demons. World-renowned Harvard symbologist Robert Langdon is summoned to a Swiss research facility to analyze a cryptic symbol seared into the chest of a murdered physicist. What he discovers is unimaginable: a deadly vendetta against the Catholic Church by a centuries-old underground organization, the Illuminati. In a desperate race to save the Vatican from a powerful time bomb, Langdon joins forces in Rome with the beautiful and mysterious scientist Vittoria Vetra.