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.

While a Navy Seal is on a secret mission, his young daughter is kidnapped; Danny must find $18.5 million in order to save his brother.

When a Detroit hit man is taken out by one of his colleagues on the streets of Oahu, Five-0 is shocked to learn the killer's surprising motives. Meanwhile, Chin puts his career on the line to help Danny get the money he needs to save his brother's life.

On the fourth anniversary of his father's death, McGarrett meets a woman who helps him reopen the last unsolved case his dad worked on before he died.

It's Halloween and Five-0 must track down a serial killer who is copying murders depicted in a cult slasher film. Meanwhile, McGarrett must help Jerry after he is kidnapped by the counterfeiters he has been tracking.

When McGarrett is kidnapped by Wo Fat, he experiences what would have happened to the team if they had taken a very different path, on the 100th episode.

While the team investigates a couple's murder in which their sons are the prime suspects, McGarrett is shocked when Aunt Deb returns to the island with her new fiancé.

It's Christmas in Hawaii and Five-0 travels to the Big Island, where Max is forced to work with a rival medical examiner after a cowboy is poisoned. Meanwhile, McGarrett pressures Danny into stealing a Christmas tree.

With the help of an ex-HPD officer-turned private detective, Five-0 tries to solve the homicide of a woman who was working for a hula dancing company that is actually a front for an escort service.

When a tourist is killed after unknowingly transporting a stolen Van Gogh, an undercover Kono and Chin enter the world of black market priceless art and are taken hostage. Also, McGarrett asks Iron Chef Masaharu Morimoto to help train Kamekona to beat Chef Sam Choy in a shrimp cook-off.

A neurosurgeon is assassinated just before performing a surgery. The investigation uncovers the truth behind the disappearance of four reform school boys over 40 years ago. Meanwhile, McGarrett's beloved Mercury Marquis is stolen by an unlikely culprit.

Five-0 must find a kidnapped patient infected with a contagious and lethal strain of bird flu which the culprits intend to weaponize.

While Five-0 hunts for a notorious criminal who has never been seen, Kono must fight for her life when she discovers the villain's identity. Also, Kono confesses to Adam that she's conflicted about their future together because of his ties to his formerly corrupt family business.

When a journalist is killed, Five-0 must use his past reporting to hunt down a presumed dead Congolese warlord who is alive and well living on Oahu. Also, as Valentine's Day approaches, Danny overreacts when Grace's texts to a boy start accidently coming up on his cell phone.

Five-0 enlists the help of a California ATF Agent to find a serial arsonist targeting couples on Oahu. Meanwhile, when Danny whisks Amber away for a romantic getaway, her abusive ex-husband tracks them down, intent on taking his wife back.

McGarrett and Danny work on their relationship while they stakeout a woman's apartment after she escapes following a diamond robbery.

McGarrett enlists Joe's help after Danny and Chin are arrested for deadly past transgressions.

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.

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.

When a performer is killed at a convention of Elvis impersonators and his body is stolen, Five-0 must track down the culprits who are after the hidden diamonds sewn into the victim’s costume. Also, Gabriel Waincroft returns to ask for Chin for help getting off the island.

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.

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.

While Five-0 investigates the murder of a bounty hunter after he apprehended a fugitive hiding out in Hawaii, Rachel reveals a long-held secret to Danny that has serious ramifications. Also, as Kono’s wedding nears, Chin voices his concerns to McGarrett that Adam is still working with the Yakuza.

On the eve of Kono’s wedding to Adam, Five-0 must stop a fanatical patriot intent on starting a new war on terror by detonating stolen nuclear warheads and framing a terrorist leader.