Episode 1 : A'ohe kahi e pe'e ai
The island of O'ahu goes on lockdown when Five-0 hunts a terrorist who starts using weaponized drones on civilians. Meanwhile, McGarrett and Danno must go for a mandated review with a psychologist, resulting in a session which looks a lot like couples therapy.
Episode 7 : Ina Paha
When McGarrett is kidnapped by Wo Fat, he experiences what would have happened to the team if they had taken a very different path. William Sadler returns as McGarrett's father, and musician Gavin Rossdale guest stars as the nefarious Johnny Moreau.
Episode 17 : Kuka'awale
McGarrett and Danny work on their relationship while they stakeout a woman's apartment after she escapes following a diamond robbery. Series star Daniel Dae Kim makes his directorial debut. Max Weinberg, Emmy Award winner Cloris Leachman, Charlie Saxton, Jon Lovitz and Jessica Lowndes guest star.
Episode 18 : Pono Kaulike
McGarrett enlists Joe's help after Danny and Chin are arrested for deadly past transgressions. Terry O'Quinn and Jimmy Buffett return.
Episode 19 : Kahania
McGarrett and Odell come under siege in Odell's barbershop when they try to protect a young man who is being hunted down by a gang. Also, Jerry is wrongfully accused of committing a series of home invasions. Michael Imperioli returns.
Episode 20 : Ike Hanau
When Grover's oldest and closest friend tells him he witnessed his wife fall off a cliff to her death, Grover's gut instinct tells him that this was no accident. Also, Danny and Dr. Shaw get trapped in an elevator with a dead body in need of processing. Mykelti Williamson, Michelle Hurd and Kim Wayans guest star.
Episode 22 : Ho'amoano
When a woman is found murdered in the hotel suite occupied by three married men, Five-0 must help the friends get over their massive hangover and retrace their steps from a wild night to find the killer. Also, Jerry witnesses a woman's kidnapping on the streets of O'ahu. Jaleel White, Pauley Shore and Kevin Farley guest star as the three married men. Real life Honolulu Police Chief Kealoha guest stars as himself.
Episode 23 : Mo'o 'olelo Pu
When Kono goes on a solo outrigger trip around the Hawaiian islands in honor of her mother, she hits a patch of wild weather and must fight to stay alive. As Five-0 searches for Kono, they investigate a man busted for cooking meth who claims he received a threat on his son's life if he didn't continue making the drug.
Episode 24 : Luapo'i
While Five-0 works the case of a murdered bounty hunter who apprehended a dangerous killer, Danny's ex-wife reveals a shocking secret to him that will change his life forever.
Episode 25 : A Make Kaua
On the eve of Kono's wedding to Adam, Five-0 learns that a stolen nuclear bomb is somewhere on the island and about to be detonated. Also, McGarrett is stunned when Catherine returns to Hawaii, while Chin confronts Adam about his lingering connections to the Yakuza.