The transition between the original trilogy and the rest of the series is marked by this season. After the third season closed out the major plot points that defined the early run, this season sets the trajectory for following seasons. Outside of Jack and Chloe, the early episodes feature a new cast, and familiar faces are slowly reintroduces as the season progresses. This allows the new characters to become defined and appreciated. Like the previous seasons, there is a shift between the first and the second half of the season, but the peril is consistently dire throughout. The early smaller focus on the terrorist family, the kidnapping of the Secretary of Defense allow the viewer to acclimate to the new tone of the season and allows Jack to transform from the bureaucrat to the super agent of the past. The relationship with Audrey, and the consequences of his actions that destroy his relationship and his hopes of a quiet life leave him at the end of the season as he was at the end of the first. The strength of the episode lies in how organically the various threats faced by the nation organically flow from each other give one of the most coherent narratives throughout the entire day. The weakest and most disruptive plot involves Driscoll's daughter, but it allows her to gracefully exit the show while maintaining a degree of humanity that otherwise would not be earned based on her actions. The introduction of President Logan allows for the return of President Palmer and the redemption of Mike Novick. Logan's passivity and indeciveness are emphasized, and strongly contrasted to Palmer, but there is enough hinted at that will payoff in future seasons. ( )