*copied from Wikipedia

   * Marcus Yallow - Main protagonist, a 17-year old high school student who enjoys understanding technology and building his own custom devices. He is the leader of his foursome of friends.
   * Darryl Glover - Marcus' best friend who attends the same high school as Marcus and is the details man of the group. He has had a crush on Van for years.
   * Vanessa Pak (Van) - 17 year old North Korean girl who attends a nearby all girls' Catholic school, she is the "ideas" person of the group. She has had a thing for Marcus for a long time, but doesn't admit it until the end of the book. Her parents managed to escape from North Korea.
   * Jose Luis Torrez (Jolu) - A brilliant high school student at a nearby Catholic school, he is the technical member of the group. Even though everyone in the group is very tech savvy, he is the most technology-oriented, doing his own programming, and working for a local ISP. He is somewhat vain and seems to work at being cool.
   * Charles Walker - Also a student at the same high school as Marcus and Darryl, he is the antithesis of Marcus. He is a bully, a brown noser and a narc for the authorities. He and Marcus have a long standing feud and detest each other.
   * Carrie Johnstone - Main antagonist and in charge of the DHS that is monitoring San Francisco. She is a cold sadistic woman to whom the ends always justify the means and enjoys abusing her power. She is mainly known as "Severe Haircut Woman" throughout most of the novel.
   * Fred Benson - One of the vice-principals at Cesar Chavez High School. He is an authority figure, clueless about technology, who has had it in for Marcus for years. He seems to be one of the primary reason for Marcus' distrust of authority figures.
   * Angela Carvelli (Ange) - She attends the same high school as Van and develops into Marcus' love interest. She is an active member of the Xnet and is very strong-willed, independent, and sexual.
   * Ms. Galvez - A social studies teacher at Cesar Chavez High School, she is a dedicated teacher and an independent thinker. She seems to be the only teacher that Marcus respects at his school.
   * Barbara Stratford - Investigative reporter for the Bay Guardian, who helps Marcus expose what the DHS has been doing.
   * Lillian Yallow - Marcus' mother, British ex-national, who helps newly immigrated Britons integrate into American life. She and Marcus have a strong bond and seem to think alike. She is a strong woman and helps mediate Marcus and his father's fights.
   * Drew Yallow - Marcus' father who has a stormy relationship with Marcus through most of the book. He was so scared by the thought of Marcus having died during the bombing, because Marcus was missing for three days, that he supports the tactics DHS employs. This leads to many arguments with Marcus despite his former mindset that was similar to Marcus'.