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.
(Cocoon) After Steve’s CIA agent friend is killed, McGarrett lets himself be captured by the group he thinks is responsible and endures a torturous sensory deprivation tank to find the killer. Also, Tani wrestles with whether or not she will tell McGarrett about the murder weapon she found at Adam’s house.
(The Man Who Fell from the Sky) When a vacationing dad on a flight to Honolulu is kidnapped and force to parachute mid-flight, Danny, Tani and Junior track him through the jungle to discover that he may not be who he seems. Also, McGarrett is threatened with a secret from his past.
(When the Sea Draws Out the Tidal Wave, the Rocks Where the Cowries Hide Are Exposed) Crime spikes when a heat wave hits Oahu, causing McGarrett and Danny to hunt down a bank thief, and Tani and Junior’s car is stolen while they’re on duty. Also, Grover plays the golf game of a lifetime, and Kamekona incites a riot by price-gouging on his shave ice.
(On the Slope of the Cliff, Not One Jutting Rock Is Hidden from Sight) Jerry accompanies Junior as he escorts a fallen soldier home to Oahu. Also, McGarrett and Danny discover a dead body when they delve into the illegal and highly profitable black market for sand.
(Nothing More for the Eyes to Search for) On Halloween, Jerry and his friends search his childhood camp for evidence to a murder he witnessed as a boy, while McGarrett investigates a little girl who drew pictures depicting the scene of a recent murder before it was discovered.
(Is Borne on the Back; Is Borne in the Arms) McGarrett crosses the line and is arrested while investigating the death of his former SEAL buddy, who died while making an emergency landing on an aircraft carrier, and the only survivor is a baby. Also, Adam returns to Oahu with some devastating news about his marriage.
(The Smoke Seen in the Dream Now Rises) McGarrett investigates a cold case from the 1940s, one that his grandfather and the famous Honolulu detective Chang Apana worked on, and he tries to deduce how the case could have been solved. Also, McGarrett and Danny get ready for the opening of their restaurant.
(Birds of a Feather) Thanksgiving brings Grover’s parents and brother Percy, Jr. to Oahu for a visit tainted by sibling rivalry, and Five-0 investigates a thief who is crushed to death by an empty safe.
(Truth Comes from the Night) A renowned urban vigilante is killed after making another citizen’s arrest, and Five-0 delves into the world of super heroes and comic books to find the killer. Also, Adam finally gets closer to finding out who killed his sister.
(When the Light Goes Out, the House Is Dark) After fighting off an assassin in his own home, McGarrett and Joe White flee to Montana to prepare for a battle against those exacting revenge for a past SEAL mission.
(Gone on the Road from which There Is No Returning) Still reeling from the murder of one of their ohana, Steve and Catherine, along with Danny, Junior and some old friends, Harry Langford and Wade Gutches, hunt down the killer.
(A Bruise Inflicted on an Innocent Person Vanishes Quickly) McGarrett and the team support Danny and Rachel by determining what happened when Grace gets into a life-threatening car accident and lands in critical condition. Also, Tani helps Koa when his rehab patient goes missing.
(Those Above Are Descending) Adam, Junior and Tani travel to the bottom of the Pacific Ocean when a murder takes place in a remote underwater lab, and the killer may still be on board.
(Depressed with the Heat of Kealwalua) While investigating Flippa’s friend’s murder, McGarrett and Grover uncover a deadly plan by an extremist group on the Island. Also, Grover has an emotional reaction to the case.
(Made Prisoner by the Reign of the Rain) As a dangerous hurricane hits Oahu, Five-0 is tasked with protecting El Diablo, a captured serial killer who is being hunted by an assassin. Also, Tani’s civilian safety check during the storm turns deadly and Rachel and Charlie evacuate to Danny’s house, where the ex-spouses reminisce.
(When Covetousness is Conceived, Sin is Born) When the top salesperson for a beauty company/pyramid scheme is murdered, Five-0 sifts through a long list of possible suspects who would want her dead. Also, Adam befriends a homeless man estranged from his family.
(Offer Young Taro Leaves To) Junior is torn between his duties as a member of Five-0 and his feelings for his former girlfriend when her new love, the father of her son, is one of the culprits in a bank-heist-turned-homicide.
(He Who Eats 'ape is Bound to Have His Mouth Itch)