: Faced with an Internal Affairs investigation regarding his past, his integrity is once again put to the test. Major Plot Arcs and Themes
Simultaneously, the core team undergoes profound transitions: Hawaii Five-0 - Season 4
The overarching narrative continues to grapple with the shadow of . A pivotal clue regarding "Shelbourne" leads Steve to suspect a blood connection, ultimately resulting in a DNA test to see if they are half-brothers. This arc emphasizes the show's recurring theme: the blurred line between family and enemy. : Faced with an Internal Affairs investigation regarding
The Evolution of Brotherhood and Duty: Hawaii Five-0 Season 4 This arc emphasizes the show's recurring theme: the
Critics and fans alike viewed Season 4 as a period of maturation. While some noted that the show occasionally "jumped the shark" with outlandish scenarios—such as the rescue mission in Afghanistan—the central "cargument" banter between McGarrett and Danno remained the series' emotional anchor. According to reviewers from TV Fanatic , the season successfully balanced serialized drama with procedural "case of the week" episodes, culminating in a high-stakes finale involving the kidnapping of Grover's daughter.
The most significant addition this season is (played by Chi McBride), the former Chicago PD SWAT commander whose initial friction with Steve McGarrett (Alex O'Loughlin) eventually evolves into mutual respect and full team membership. This dynamic provides a fresh perspective on the team's "immunity and means" status, as seen on Fandom .
: After retiring from the Navy to join Five-0, her tenure is cut short by a "debt of honor" that takes her to Afghanistan, marking her departure from the main cast.