Shimomura tells how he gained instant celebrity by helping the FBI nab famed hacker Kevin Mitnick; Markoff, a San Francisco-based reporter, made Shimomura an overnight sensation with front-page stories in the New York Times. Brought to the US from Nagasaki in the late 1960s when his biochemist father joined the Princeton faculty, Shimomura (now 31, the same age as Mitnick) proved a natural with computers early on. A Cal Tech dropout, he has held top research posts at blue-chip institutions like the federally financed San Diego Supercomputer Center (his current employer) and consults for a wealth of Silicon Valley enterprises and government agencies. While on a skiing holiday toward yearend 1994, Shimomura received word that an intruder had penetrated his systems and was monkeying with the files. Taking the incursion personally, he launched a determined effort to track and trap the assailant through the Internet. His efforts proved successful, and the Feds nabbed Mitnick in Raleigh, N.C., during the second week of February. While the details of how Shimomura trailed his quarry via cellular phone exchanges and other means are captivating, the many particulars of his life are less so. The nominal author also fails to note that the charges of telecommunications fraud originally leveled against Mitnick in North Carolina were subsequently dropped, and he was returned to California to face trial on older counts (including parole violation). Nor does the software sleuth make a very good job of putting cyberspace crime in perspective, thereby diminishing the significance of his own accomplishments. Although fascinating when the author sticks to techno-detection, there's too much background noise and score-settling with those who let him down during the cross-country chase. Readers who want the whole story should check Jonathan Littman's broader-gauged The Fugitive Game (p. 1687).