S4E1 - Aloha Ke Kahi I Ke Kahi (We Need Each Another)
After McGarrett and Wo Fat narrowly escape from maximum security, gunmen storm Five-0 headquarters, compromising Kono and Adam's secret location in Hong Kong and forcing McGarrett to break the law and turn on his own in order to find a kidnapped Catherine.
S4E2 - A‘ale Ma‘a Wau (Fish Out of Water)
As the Five-0 team members investigate a murder, they are led to a Texas ranger who came to Hawaii to look for his daughter; Adam and Kono fight to stay alive.
S4E3 - Ka 'oia' i' o ma loko (The Truth Within)
A conspiracy theorist helps Five-0 when a missing artifact is the key to solving a double murder.
S4E4 - A Ia La Aku (From This Day Forward)
Five-0 investigates the murder of a wedding crasher, and their prime suspect is the runaway bride. Meanwhile, Danny makes a big decision regarding his relationship with Gabby.
S4E5 - Kupu‘eu (Fallen Hero)
As Catherine’s seemingly harmless surveillance job takes a deadly turn, Adam considers making the ultimate sacrifice to save Kono.
S4E6 - Kupouli ‘La (Broken)
When Halloween comes to Hawaii and a zombie-like man is shot, Five-0 races to stop a madman who is conducting experiments on humans.
S4E7 - Ua Nalohia (In Deep)
While working the murder case of an undercover ATF agent, McGarrett and the Five-0 team are tasked with watching Mary’s newly adopted baby after she gets sick.
S4E8 - Akanahe (Reluctant Partners)
McGarrett and Grover must work together to protect national security after they are tasked by the Governor to serve a warrant to a young computer hacker.
S4E9 - Hau‘oli La Ho‘omaika‘i (Happy Thanksgiving)
As Thanksgiving approaches, Five-0 investigates the murder of a secret service agent just as the President travels to Oahu. Also, McGarrett's Aunt Deb visits, bringing with her a shocking secret.
S4E10 - Ho‘onani Makuakane (Honor Thy Father)
The attempted murder of a Pearl Harbor veteran leads Five-0 to use decades old evidence to investigate a deadly crime committed within the internment camps on Oahu during World War II.
S4E11 - Pukana (Keepsake)
An investigation involving a potential serial killer puts Chin's life in danger; Grace and Danny find a mysterious puzzle box.
S4E12 - O Kela Me Keia Manawa (Now and Then)
Captain Grover is aided by McGarrett in his search for a friend who has disappeared, after it seems like he's committed murder. Kono persists in her quest to find Adam.
S4E13 - Hana Lokomaika‘i (The Favor)
Chin is questioned about his father's murder and how his relationship with Malia and her family could have adversely affected the investigation.
S4E14 - Na hala a ka makua (Sins of the Father)
An escaped convict who wants Five-0 to prove his innocence abducts Danny and McGarrett; Grace punches a person at school.
S4E15 - Pale'la (Buried Secrets)
A real estate agent is found dead inside the walls of one of his listings. Meanwhile, Danny's mother makes an unexpected visit and brings with her some shocking news.
S4E16 - Hoku Welowelo (Fire in the Sky)
A triple homicide is linked to a secret, downed Chinese satellite; Danny's mother goes on a ride-along with Grover.
S4E17 - Ma Lalo o ka 'lli (Beneath the Surface)
A man is shot as his daughter is abducted; Danny tries to reunite his parents; Jerry finds a code on McGarrett's champ box.
S4E18 - Ho‘i Hou (Reunited)
Fan-built Episode. Five-0 investigates when the daughter of a macadamia nut tycoon is murdered with a stiletto heel during Chin’s high school reunion.
S4E19 - Ku I Ka Pili Koko (Blood Brothers)
Five-0 is set up when a bad tip leads them to an abandoned building that is rigged to explode with McGarrett and Danny trapped inside.
S4E20 - Pe‘epe‘e Kānaka (Those Among Us)
The investigation of a murdered pool cleaner leads the Five-0 team to a possible terrorist cell of radicalized students plotting an attack on U.S. soil.
S4E21 - Makani 'Olu a Holo Malie (Fair Winds and Following Seas)
McGarrett and Catherine travel overseas to Afghanistan to stop the Taliban from harming a young boy whose family saved Catherine's life years ago.
S4E22 - O ka Pili ‘Ohana Ka ‘Oi (Family Comes First)
When Grover's daughter is kidnapped by an old nemesis, he is forced to help steal $100 million in order to get her back. Meanwhile, Wo Fat escapes prison and heads back to Oahu.
