Hawaii Five-0

A new ally assists McGarrett and Five-0 as mob bosses on the island become targets of an assassin. Meanwhile, Five-0 bids farewell to one of their members.

Tani and Junior find themselves and several civilians trapped inside a deadly tunnel collapse and must work together to plot an escape. Meanwhile, Five-0 investigates the cause and identifies the culprits responsible for the cave-in. Eddie the dog uses his field experience to sniff out a bomb that has been planted in McGarrett’s home.

Five-0 launches an investigation after a plane that crashed into the Pacific in the 1980s is discovered, containing a recently murdered scuba diver. Meanwhile, as MacGarrett and Quinn narrow down the identity of the person who planted a bomb in his garage, and he formally invites her to join Five-0, she is arrested on charges of money laundering.

Five-0 enlists imprisoned hacker Aaron Wright to help when a young girl is reported kidnapped. However, upon rescue, the culprits are found dead, the girl is confirmed safe, and it is revealed she is not who she claims to be.

It's Halloween when Five-0 investigates a home invasion that turns deadly after a dangerous "monster" escapes from the basement. Meanwhile, Max returns to Oahu with a very special guest.

McGarrett and the team launch an investigation into a deadly hit-and-run involving a driverless car that was transporting heroin, uncovering what may be a new method for drug distribution. Meanwhile, Tani and Quinn are tasked with overseeing a pair of YouTubers who are given a ride-along with Five-0.

Steve McGarrett is informed by the CIA that his mother has gone rogue during her undercover mission and may be responsible for her partner's death. Determined to bring her home and clear her name, he takes matters into his own hands and travels to Mexico alone.

Five-0 partners with a DEA agent to investigate a killer whose plane crashed in the jungle, carrying $10 million worth of heroin. Meanwhile, Grover is excited when his niece, Siobhan, arrives to try out for the University of Hawaii basketball team.

On Thanksgiving, Junior and Tani pursue the thief who robbed Junior's parents' home, while Five-0 investigates the murder of a beloved philanthropist and the theft of his ultra-valuable koa tree. Meanwhile, Danny moves in with McGarrett.

When Adam's girlfriend, Tamiko, is kidnapped right in front of him, he withdraws from Five-0 and disregards all the rules in an effort to rescue her. At the same time, Five-0 investigates three homicides that initially appear to be unrelated.

When Five-0 investigates a tourist helicopter that was shot down by a missile, they trace the stolen artillery to a ghost from McGarrett’s past. After Adam’s ordeal in rescuing Tamiko and reconnecting with the Yakuza, he makes a bold decision about his future with Five-0.

When a list containing the identities of undercover CIA agents is stolen, Steve and Five-0 recruit Magnum, Higgins, Rick, and TC to recover it and safeguard national security. Additionally, Higgins offers Tani some personal advice.

Grover and the Five-0 task force investigate a murder that occurs at a private golf course, where a man is found frozen to death inside the locker room's cryo-chamber. Meanwhile, McGarrett accompanies Danny on a lead to locate the father of a boy who has been bullying Charlie.

Soon after Danny meets the girl of his dreams, they are involved in a potentially fatal car accident in a remote area. Meanwhile, McGarrett recruits Quinn and Tani to assist when Eddie the dog begins displaying signs of PTSD.

When Grover's niece, Siobhan, disappears from the police academy and it is revealed that her boyfriend is an undercover member of the Yakuza, Adam may be the only one who can rescue her.

On Valentine's Day, Tani and Noelani are taken hostage during a robbery at a convenience store. Meanwhile, Five-0 investigates the disappearance of a Thai diplomat's wife, who confesses to the crime, though Danny suspects she is shielding the true perpetrator.

Harry Langford assists Five-0 in investigating a string of murders that mirror the plot of an unpublished crime novel from the 1920s. Meanwhile, Tani and Junior's friendship develops in a significant new direction.

As Five-0 investigates a murder aboard a cargo ship where pirates disguised themselves as Coast Guard members to gain access, Adam secures the evidence he needs to dismantle the Island's Yakuza operation. Quinn assists Noelani when she begins to suspect that her uncle's death was not due to natural causes.

When a rancher is murdered after discovering human skeletons on his property—where local legend claims Civil War-era gold coins are buried—Five-0 launches an investigation. At the same time, Quinn's former stepdaughter, Olivia, contacts her for assistance after her father fails to return home.

In one episode, Five-0 investigates a plot to rob tourists, while Tani assists Girard Hirsh (played by Willie Garson) in proving the innocence of his elderly uncle, who is suspected of murder. Meanwhile, Tani and Junior explore the complexities of being in a new relationship.

After Steve receives a posthumous letter from his mother containing a cipher, Danny is attacked by someone willing to kill to steal it. Five-0 must assist Lincoln Cole, an anonymous good Samaritan who has become a target of dangerous individuals.

Danny is kidnapped and seriously injured by Wo Fat's wife, who is seeking the cipher left to Steve by his mother. Steve works to solve the case his father left for him 10 years earlier.