At Large is the astonishing, never-before-revealed tale of perhaps the biggest and certainly the most disturbing computer attack to date, with ominous implications for the Internet, the digital highway over which much of the nation's business is now conducted.

For two years a computer break-in artist known only as "Phantom Dialer" seized control of hundreds - perhaps thousands - of computer networks across the country and around the world. Frightened network administrators watched helplessly as the intruder methodically slipped into universities, corporations, banks, federal agencies, and military facilities, including top-secret weapons-research sites.

Working up to twenty hours a day, Phantom Dialer obsessively broke into one network after another - and no one knew who he was or what he was after. Was he a spy? Was he laying the groundwork for a single, massive theft?

As the number of victims mounted, Phantom Dialer became the subject of the first major investigation of the FBI's new computer-crime squad and one of the biggest manhunts in the history of electronic crime. But when FBI agents finally burst into Phantom Dialer's house, they were stunned and dismayed by what they found. The decision was made not to prosecute but instead to keep the story quiet.

The story of Phantom Dialer demonstrates the vulnerability of the global network: anyone can break in almost anywhere. Indeed, though few recognize it, the massive crime wave has already begun.