The action of this exciting thriller takes place in The National Security Agency (NSA) and in Seville. At the very beginning the principal hero who was recently fire from NSA dies from presumable heart attack. But even being dead he continues to exist in the form of his computer program called Digital Fortress. It generates unbreakable codes which can transform NSA's supercomputer TRANSLTR. The problem arises because the programmer left a description code on his ring. Finding this ring creates the plot of the book. Trevor Strathmore who headed NSA cryptology department sends Linguist Dave Becker to find the ring while he himself and Becker's lover Susan Fletcher serving as a senior code-cracker in NSA think over weaknesses in TRANSLTR. Meanwhile in Seville we follow the chase scenes. The main events, however, are happening at NSA. Among murder, infernos and explosions it suddenly becomes clear that Strathmore possesses an agenda aiming beyond breaching Digital Fortress. Cyber-minded readers will be carried away by Brown's capabilities at hinting and concealing Strathmor.