Marcus and his friends are in the wrong place at the wrong time when the Bay Bridge blows up, and they're quickly taken into custody by the DHS--Department of Homeland Security. Individually, they're questioned, then interrogated. When he's finally released, Marcus swears revenge, and launches a campaign to take down the DHS. He knows he's under strict surveillance, so he utilizes a small hack for XBox system, loading on a new operating system (Paranoid Linux) and setting up an enormous amount of security. He distributes discs and instructions to teens all over the Bay area, building up what becomes known as the Xnet, and the movement is born. DHS is tracking citizens via RFID in transit passes and other cards: the Xnetters clone the cards and swap data, making every person's movements look suspicious. DHS calls nearly any youth gathering a riot: the Xnetters stage huge concerts and get press coverage. Marcus's movement is gaining ground, but it's only a matter of time until the DHS catches up to him, in spite of all his techno-security measures. Keeping himself safe is a high priority, but keeping himself--and others--free is even higher. 
 Calling this a dystopia is a little dicey; it makes a political statement I'm not sure I want to be making. But it is about the intrusiveness of surveillance, the flaws in the "I have nothing to hide" logic, and the true costs of allowing someone else to determine what "safety" means and how to secure it. 
 Obvious parallels to 1984 and slightly-less-obvious parallels to The Trial, with lots of techno-geekery thrown in. It's subject to Doctorow's usual flaws (namely that he gets caught up in explaining the technology and loses the thread of the story he's telling), but this time the several threads he's exploring (DHS, online security & encryption methods, tracking) all fit together. Recommended for budding (and adept) hackers and online technologists; even with all the explanations, non-techies may have trouble following the action.