Kim Woo-Hyun (So Ji-Sub) is the only son of a high ranking police officer. Woo-Hyun entered the police academy ranked first and graduated from the academy ranked first. As a detective, he then joins the cyber investigation department. Woo-Hyun then works to reveal the secrets of those that hide within the cyber world.

Kim Woo-Hyun leads the cyber investigation team and works to take down an illegal international gambling website. South Korea, Hong Kong and China all cooperate to arrest those involved with the website at the same time. When Kim Woo-Hyun and his team raid the location of the site, the data is destroyed by a program set up by Hades. Nevertheless, Kim Woo-Hyun and his team uses a traceroute to locate Hades.

Meanwhile, an online rumor spreads about a sex scandal involving popular actress Shin Hyo-Jung (Esom). Shin Hyo-Jung leaves the message "I want to die" on her twitter account and then kills herself by jumping out of her apartment. Kim Woo-Hyun and Detective Yoo Gang-Mi (Lee Yeon-Hee), still following the path of Hades, arrives at the actresses apartment and takes her laptop, which Hades hacked.

In the basement parking lot, Detective Yoo Gang-Mi runs into Reporter Park Gi-Young (Daniel Choi). Park Gi-Young asks Detective Yoo Gang-Mi if she is sure actress Shin Hyo-Jung's last tweet was indeed posted by the actress herself? There seems to be a rumor that her last tweet was not actually posted by herself. Detective Yoo Gang-Mi later checks actress Shin Hyo-Jung's laptop and discovers that the tweet was not posted from her laptop. The cyber investigation team now believes another person may have been there when the actress died.

Meanwhile, Detective Kwon Hyuk-Joo (Kwak Do-Won) also investigates the death of actress Shin Hyo-Jung. A TV announcement is then made by Detective Kwon Hyuk-Joo's boss (against the advice of Detective Kwon Hyuk-Joo) that actress Shin Hyo-Jung killed herself. Suddenly, the TV video feed cuts to actress Shin Hyo-Jung falling out of her apartment. Cyber investigation team leader Kim Woo-Hyun, using his computer near a large building, chases Hades who cut into the TV announcement video feed. Finally, Kim Woo-Hyun catches Hades on the subway. Kim Woo-Hyun is shocked when he learns that Hades is his ex-roommate at the police academy Park Gi-Young and now reporter. Park Gi-Young insists that he did not kill actress Shin Hyo-Jung. He states that he received an email a week ago, promising him a large sum of money if he finds the phantom file which actress Shin Hyo-Jung possesses. He also says the real killer wore a watch having a world map and then runs from Kim Woo-Hyun.(**sumber sini)