Hawaii Five-0 is a contemporary take on the classic series about a new elite federalized task force whose mission is to wipe out the crime that washes up on the Islands' sun-drenched beaches. Detective Steve McGarrett, a decorated Naval officer-turned-cop, returned to Oahu to investigate his father's murder and stayed 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 is Detective Danny "Danno" Williams, a relocated ex-New Jersey cop - a working man in paradise who prefers skyscrapers to the coastline - but who's committed to keeping the Islands safe for his young daughter; Chin Ho Kelly, an ex-Honolulu police detective and former protégé of McGarrett's father who was wrongly accused of corruption; Dr. Max Bergman, the quirky coroner; Chin's cousin, Kono Kalakaua, a beautiful and fearless native; and Captain Lou Grover, who formerly headed Hawaii's SWAT unit. Joining them is Jerry Ortega, a former classmate of Chin's and the Island's local conspiracy theorist. 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.
Five-0 enlists the help of an old friend when the boss of a major crime family is murdered, triggering revenge killings across the island. Also, MacGarrett and Danny begin sorting out particulars in their new restaurant venture.
At Halloween, Five-0 must investigate a string of murders that mirror stories from well-known Hawaiian folklore. Also, Grover is called to visit a man hours away from execution who may hold the key to a case that has plagued Grover for years.
The murder of two tourists leads Five-0 to a man suffering from multiple personality disorder, where one of them becomes violent and another is a child. McGarrett is accompanied on the case by a stress management consultant, whom Danny and the others have hired to help him manage his health.
When an FBI agent who was cracking down on organized crime is killed, McGarrett rounds up every gang-related criminal on the island to find the culprit. Also, McGarrett tasks Adam with forming a new division within Five-0 to take on organized crime.
When the corpse of a diamond smuggler is stolen from a graveyard, Five-0 tracks down his partner, Voss, who will stop at nothing to retrieve their latest batch of contraband. Also, Adam recruits a new confidential informant, Jessie Nomura; Tani gets a devastating call; and McGarrett tasks Pua to find his and Danny's stolen tools.
McGarrett and Danny investigate the murder of a private detective whose client was killed the same way, and Adam sends Jessie into a dangerous situation with disastrous consequences. Also, Danny's uncle, Vito, comes to town to help Danny and McGarrett get their restaurant up and running.
Tani and Junior go undercover as prospective parents in order to infiltrate a private school where the headmaster was murdered. Also, Adam's life is on the line when he is held captive and forced to produce a hidden massive amount of money.
The ex-wife of the man who shot Danny comes to Oahu and reveals how Danny's protection during a dangerous domestic dispute when he was in New Jersey helped save her life. Also, Tani and Junior are assigned to walk the beat as uniformed officers for the day, and Adam is framed for the murder of the crime boss he has been tracking.
Catherine Rollins recruits McGarrett and Jerry to help her track down a uranium deposit thought to be hidden on an abandoned Hawaiian island before a suspected terrorist can make dirty bombs with it. Also, when Junior falls and is trapped in a ravine, he reflects on his estranged relationship with his father.
Harry Langford enlists McGarrett and Danny's help to track down Lady Sophie, a teenage British royal who has run away while under his protection. Also, Grover, Tani and Junior work a 25-year-old murder case after a mysterious Betamax tape arrives at 5-0 headquarters.
Five-0 must help Duke after he is forced to steal crucial evidence from the police locker in exchange for his kidnapped granddaughter. Also, Jerry goes undercover at a mental health facility in order to solve a murder.