Detective Steve McGarrett, a decorated Naval officer turned cop, returned to Oahu after Hawaii's former governor persuaded him to head up the new team: his rules, no red tape and full blanket authority to hunt down the biggest "game" in town. Joining McGarrett are Detective Danny "Danno" Williams, a relocated ex-New Jersey cop who is committed to keeping the islands safe for his children; Captain Lou Grover, who formerly headed Hawaii's SWAT unit; Jerry Ortega, the islands' local conspiracy theorist; and Tani Rey, a bold, recent police academy graduate.
Helping them is Adam Noshimuri, a friend with old ties to a deadly crime family; Junior Reigns, a former SEAL who comes to McGarrett looking for a job; Kamekona, a local entrepreneur who has his pulse on the Island; Sgt. Duke Lukela, a trusted member of the HPD; and medical examiner Dr. Noelani Cunha. The state's brash Five-0 unit, who may spar and jest among themselves, remain determined to eliminate the seedy elements from the 50th state.
(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.
(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.
(The Truth Within) A conspiracy theorist helps Five-0 when a missing artifact is the key to solving a double murder.
(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.
(Fallen Hero) As Catherine’s seemingly harmless surveillance job takes a deadly turn, Adam considers making the ultimate sacrifice to save Kono.
(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.
(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.
(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.
(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.
(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.
(Keepsake) Chin’s life is put in danger when a murder investigation reveals that the person behind the crime may be a serial killer. Meanwhile, Danny and Grace find a mysterious puzzle box washed up on the shores of Oahu.
(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.
(The Favor) Internal Affairs questions Chin about his father’s murder 15 years earlier and how his then-new relationship with Malia and her family might have hurt the investigation.
(Sins of the Father) McGarrett and Danny are kidnapped by an escaped convict who wants Five-0 to prove he is innocent. Meanwhile, Grace gets into trouble when she punches someone at school.
(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.
(Fire in the Sky) Five-0 investigates a triple homicide connected to a downed top-secret Chinese satellite, while Grover takes Danny’s mother on a ride-along.
(Beneath the Surface) Five-0 aims to uncovers the sordid truth when a girl is taken from her home and her father is shot in the process. Meanwhile, Danny tries to get his parents back together and Jerry deciphers a code he found on the bottom of McGarrett’s champ box.
(Reunited) Five-0 investigates when the daughter of a macadamia nut tycoon is murdered with a stiletto heel during Chin’s high school reunion.
(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.
(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.
(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.
(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.