 In the hostage situation, the FBI Crisis Negotiation Unit is typically called upon to deal with the hostage-taker.Although the series has six main characters, Matt Flannery and Emily Lehman are considered to be the protagonists of the series as a subplot concerning their relationship is featured in each episode.Although the show lost more than half of its audience after its premiere, Fox ordered 6 more episodes in November 2006, bringing the total number of episodes to 18 for the season.