Making it his business to track down criminal activity through the web, Guido Rudolphi, the Sherlock Holmes of the cyber world, considers himself a legal hacker. "So much more information can be accessed, quite legally, than the individual user would ever imagine." Rudolphi has taken advantage of this new free-flow of online information to catch paedophiles, fraudsters, and even unearth international cells of Al-Quaeda. He demonstrates how it takes less than twenty minutes to establish a person's credentials, locate them and hand them over to the police. "People seem to think they're anonymous online, that nothing can happen to them there - that's very naive."