Five-0 investigates the murder of a shipping businessman who was supposed to be participating in a historical Hawaiian battle reenactment.

When the bodies of two serial killers are found on Five-0 property with chess pieces in their mouths, McGarrett and the team hunt for a vigilante as fear grows that tourists aren't safe in Hawaii.

Five-0 works with a British secret agent who is on a very secret and personal mission to track down a deadly device and a dangerous terrorist.

When FBI Profiler Alicia Brown finds a body in her bed, she is forced to join McGarrett in the hunt for the chess-piece killer. Also, Kono reconnects with a former surfing competitor, who is now a disabled and homeless war vet

Five-0 investigates the 10-year-old cold case of a missing teen when a boy suffering from PTSD undergoes hypnosis and realizes he may have witnessed her murder. Also, Danny's sister, Bridget (guest star Missy Peregrym), visits Oahu for a business conference, and he suspects that she may be getting too close to a co-worker.

As Max prepares to say goodbye to his Five-0 ohana, they must investigate a murder during a police convention on the Island.

Five-0 uncovers the possibility that a Nazi war criminal may be hiding in an old leprosy colony.

McGarrett and Danny finally track down the missing uranium, which has been used to build a bomb located in the middle of the jungle. Now, they must carefully extract the unstable explosive through treacherous terrain before it detonates.

McGarrett and Kono suspect that an abused young girl may be the victim of a sex trafficking ring on the Island. Also, Chin and Grover investigate a murder at a sober living facility.

Five-0 helps PI Harry Brown work the case of a kidnapped wealthy woman whose husband may have something to hide. Also, Rachel tells Danny that she is getting a divorce from Stan.

McGarrett and Five-0 are captured and face certain death after tracking a dangerous nemesis to the Island of Lanai. Also, Grover takes his son to Chicago where he testifies against a dirty cop from his past.

McGarrett puts his life in lethal danger when Five-O puts a risky plan to rescue a group of young girls from a sex trafficking ring in motion, Kono decides to make a life- altering choice because of the unique strain caused by the case.

McGarrett and his team go on the trail of an escaped prisoner convicted of arson.

McGarrett and Five-0 help save an injured police dog and in turn use him to find who killed his partner and ambushed his team making a drug bust. McGarrett receives a visit by a former SEAL, who asks McGarrett for a job on the task force.

Local big shot crime boss Jimmy Okada gets hit in a rather spectacular fashion, and Five-O's old friend from MI5, Harry Langford, lends a hand on the case.

The lives of Five-0's informants are in danger when the HPD system is hacked and one ends up dead, forcing McGarrett to enlist the help of hacker Aaron Wright (Joey Lawrence), who he just imprisoned. Joey Lawrence Returns as Aaron Wright.

Five-0 investigates a series of crimes based on legendary island folklore.

While trying to solve the murder of two tourists, Steve has to deal with a stress management consultant his friends have hired.

McGarrett and Adam join Junior at a bank heist in progress, forcing all of them to make difficult decisions in how to proceed into the bank and after the suspects. Tani has issues with a family member and gets advice from Lou.

McGarrett poses as a pilot to investigate the cause of a plane crash that led to the death of a pilot in an air race.

When investigating a deserted yacht adrift at sea, McGarrett, Danny, Tani and Junior are exposed to a deadly bioweapon and the rest of Five-0 have only eight hours to find an antidote.

When Danny is shot while quarantined in the hospital with McGarrett, Tani and Junior, he's left unconscious and clinging to life, imagining a future for everyone in Five-0.

Danny, still recovering from his gun shot wound is telling his son Charlie a bed time story who Steve and a group of veterans are hunting down some fake Santas who robbed a money truck.

McGarrett rounds up every gang-related criminal on the island to find the culprit behind the killing of an FBI agent who was cracking down on organized crime.

When a man accused of killing his wife threatens to kill himself, Grover reveals how he was once on the brink of suicide himself.

When a corpse is stolen from the cemetery, the team races to find out who the man was and why he was taken; Adam recruits someone to become an informant; Tani receives devastating news.

He Puko'a Kanu 'Aina- McGarret and Danny investigate the murder of a private detective whose client was killed the same way.

Five 0 investigate the murder of the headmaster of a private school sending Tani and Junior undercover as prospective parents. Meanwhile Adam is forced to produce a huge amount of hidden money to save his life.

Adam's mission to take down organized crime goes sideways when the bait he used falls into the wrong hands; Adam begins to doubt Jessie's allegiance.

A flashback about the case that changed Danny's life and an answer about who shot him by meeting a woman who was married to the shooter. Jimmy Buffett returns, Alex O'Loughlin directs his first episode and plays the guitar.

A hitman, Leroy Davis (Frankie Faison), McGarrett's father failed to arrest comes to McGarrett to finally confess his crimes and admit where he buried his victims. Also, Jessie makes a dangerous decision that could ruin Adam's life.

Catherine returns to Oahu, Hawaii, U.S.A. to ask Five-O for some help in order to follow up on a lead for one of her Central Intelligence Agency cases. (#188)

Harry Langford enlists McGarrett and Danny's help to track down a teenage British royal who has run away while under his protection; Grover, Tani and Junior work a 25-year-old murder case.

Duke is forced to steal crucial evidence from the police locker in exchange for his kidnapped granddaughter; Jerry goes undercover at a mental health facility to solve a murder. (#190)

Steve and Five-O take on the mob when a former boss is killed; Junior's friend is on the run after witnessing the murder. (#191)

Steve joins Junior and his SEAL team on a mission to capture an elusive person who is holding his mentor hostage; Gerard and Kamekona help Lou and Tani on a murder case involving art stolen by Nazis in World War 2. (#192)

The team discovers a Russian spy ring hiding on Oahu, Hawaii U.S.A. when one of their submarines appears off the coast. (#193)

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.

When a vacationing dad on a flight to Honolulu is kidnapped and forced 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.

The whole island is collapsing under a heat wave. Lots of people running wild and Danny and Steve are chasing a murderer.

SO2 Junior Reigns and Jerry Ortega escort U.S. Air Force SSGT Kaliko Christopher coffin from Dover Delaware to Hawaii. Duke is forced to Retirement. Steve and Danno investigate Illegal Black Market sand.

Young Jerry witnessed a murder while at camp in 1982. He's telling this story to his friends while going back to the camp in the present day. He wants to search for the body before developers level the property. A woman watching a news story about a murder realizes that her daughter drew a picture of the crime scene three days earlier. Jerry's most likely site for the body is on the property line of Bo Bradley, who Jerry thinks is the Axe Man. McGarrett and Junior interview the girl. Katie. She says her friend Molly drew the picture. Noelani shows up to help hunt for the body with ground-penetrating radar. in 1982, Jerry breaks into Bradley's house and ran away screaming after Bradley finds him. Noelani finds a bone, but it's canine. Jerry keeps digging because he thinks there's a body underneath, while everyone else leaves as it starts pouring. Three of Katie's pictures were drawn by someone else. Katie's parents see this girl, Molly, on the monitor but she escapes. Everyone's phones and keys are missing at the camp. Tani finds a woman that may have been attacked by the murderer. McGarrett thinks the drawings may be three different redheads. Jerry found human remains, but he's being followed by someone. Gordie knocks on the door and spooks everyone. He took the keys and phones. He goes to get them, but his throat gets slashed. It's the ax man, who set the cabin on fire. They have to run out, but Bradley shoots the ax-man, who is the kids' old camp counselor. The serial killer is Molly's father, who went nuts when her mother divorced him. Jerry goes back to thank Bradley and apologizes to him. Molly's mother comes to get her. Captain Keo said the gun in Adam's house was the one that killed Noriko.

McGarrett crosses the line and is arrested while investigating the death of his former SEAL buddy, who died on an aircraft carrier, and the only survivor is a baby. Also, Adam returns to Oahu with some devastating news about his marriage.

A cold case of Chang Apana (a real life detective in 1930s Honolulu) lands in Steve's lap. This leads to the crew working on the case in a 1940's world.

Lou has his family visit for Thanksgiving and his longstanding feud with his brother is on once again. A house thief is found dead in a very strange way while in the process of committing the crime.

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.

A mission from Steve's past brings what is left of his SEAL team together to protect themselves from the group that wants them dead while Five-O looks for the man who took on McGarrett by himself.

Steve, Catherine, Danny, Junior, & old friends hunt the killer of one of their ohana. Tani & Grover investigate a missing bag of human bones.

McGarrett and the team support Danny & Rachel by determining what happened when Grace gets into a life-threating car accident; Tani helps Koa when his rehab patient goes missing.

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.

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.

While a hurricane lashes Oahu, the Five-0 must house a federal prisoner with a history of escaping. Danny has houseguests during the storm, while an evacuation patrol puts Tani in a dangerous situation.

A woman dies suspiciously while swimming as part of a mermaid troupe, and Adam throws more than a helping hand to a down on his luck drunkard vagrant.

Five-O has to chase down a group of murderous bank robbers after they just shot their way out of the bank.

Tani and Junior go under cover at a gym to track down a deadly batch of steroids; Danny and MacGarrett work as bodyguards for Danny's high maintenance ex-mother-in-law, a famous romance novelist with whom he has never gotten along.

The team investigates the murder of a window washer and finds that the victim is actually a renowned street artist; Grover and Adam look into the murder of a gambler; Junior helps his father when they are reminded of his sisters death.

Five-0 must locate a teen girl who purchased a gun from a junkie, and discover that the firearm, over the course of decades, has affected all of their lives.

Five-0 investigates the murder of a man whose body may hold the key to a 20-year-old case involving a kidnapped girl whose father never stopped looking for her.

While Adam investigates the murder of an undercover FBI agent about to wed the daughter of a Yakuza leader, Noelani is held hostage and forced, along with her mentor Dr. Chu (Page Leong), to operate at gunpoint on a criminal.

McGarrett helps his sister spy on shady neighbors; a ride-share driver and his passenger are murdered; the team teases the youngest members when Junior escorts Tani to a wedding.

Fugitive hacker Aaron Wright (Joey Lawrence) resurfaces to ask Five-0 for help when his co-workers at the NSA, which he has been working for, are all murdered. Also, Junior speaks at the parole hearing of the drunk driver who killed his sister.

Five-0 continues to hunt down escape criminal Aaron Wright before he can sell cyber-weapons to the highest bidder; the lives of McGarrett and the team members are put in danger when a visitor comes to headquarters to make amends.

A new ally helps McGarrett and the team when mob bosses on the island are targeted by an assassin; the team says goodbye to one of its own.

Tani and Junior must plot an escape for themselves and several civilians after they become trapped inside a deadly tunnel collapse; Eddie the dog sniffs out a bomb that has been planted in McGarrett's home.

A plane that mysteriously crashed into the Pacific in the '80s is found, but with a recently murdered scuba diver inside; McGarrett and Quinn zero in on who planted the bomb in his garage; McGarrett formally asks Quinn to join the team.

Five-0 enlists imprisoned hacker Aaron Wright to help when a young girl is reported kidnapped.

Five-0 investigates a deadly home invasion after an extremely dangerous prisoner escaped from the basement. Max returns to the island with a guest.

A deadly hit-and-run involves a driverless car carrying heroin; Tani and Quinn are stuck with a pair of YouTubers who are brought on a ride-along.

When the CIA informs McGarrett that his mother has gone rogue on her undercover mission and may have killed her partner, Steve goes solo to Mexico to bring her home and prove her innocence.

Five-O teams up with a DEA agent to search for a killer whose plane crashed in the jungle with $10 million worth of heroin on board. Also, Grover is thrilled when his niece Siobhan comes to try out for the University of Hawaii basketball team.

It's Thanksgiving, and while Junior and Tani track down the thief who robbed his parents' home, Five-O investigates the murder of a beloved philanthropist and the theft of his ultra-valuable koa tree. Also, Danny moves in with McGarret.

When Adam's girlfriend, Tamiko is kidnapped right in front of him, he shuts out Five-O and breaks all the rules in order to get her back. Also, Five-O investigates three seemingly unconnected homicides.

A tourist helicopter is shot down by a missile; a search for stolen artillery leads to a ghost from McGarret's past -- Wo Fat; Adam makes a bold decision about his future.

Five-0 enlists the help of Thomas Magnum to retrieve a stolen list of undercover CIA agents.

Grover and the team investigate a murder at a private golf course involving a man who was frozen to death in the locker room's cryotherapy chamber; McGarrett tags along with Danny to a school meeting.

Soon after Danny meets the girl of his dreams, they get into a potentially fatal car accident in an area far from help. Also, McGarrett enlists Quinn and Tani to help when Eddie the dog suddenly shows signs of PTSD.

When Grover's niece, Siobhan goes missing from the police academy and it's discovered her boyfriend is an undercover member of the Yakuza, Adam may be her only hope of rescue.

On Valentine's Day, Tani and Noelani are held hostage during a convenience store robbery. Also, Five-0 investigates the murder of a Thai diplomat whose wife confesses to the crime, but Danny suspects she's covering for the real killer.

Harry Langford helps Five-0 investigate a series of murders that follow the plot of a fabled unpublished crime novel from the 1920s. Also, Tani and Junior's friendship takes a meaningful new turn.

Dr. Noelani Cunha's uncle dies mysteriously and she sets out to discover what really happened to honor his memory, and arrest his murderer.

Five-0 investigates when a rancher is murdered after he uncovers human skeletons on his property where legend says that Civil War-era gold coins were buried. Also, Quinn's former stepdaughter, Olivia (Siena Agudong), reaches out to her for help after her father doesn't come home.

The team investigates a scheme to rob tourists; Tani helps Girard Hirsh prove the innocence of his elderly uncle when he's suspected of murder; Tani and Junior work on the nuances of being in a new relationship.

Two bank robbers are on the run and take a family hostage. Luckily a good Samaritan saves them, but at the same time crosses a crime boss. Also the mystery surrounding Doris' letter thickens.

Danny is abducted and badly wounded by Wo Fat's wife, who is after the cypher Steve's mother left him. Also, Steve finally solves the case his father left for him 10 years ago.

While Adam investigates the murder of an undercover FBI agent about to wed the daughter of a Yakuza leader, Noelani is held hostage and forced, along with her mentor Dr. Chu (Page Leong), to operate at gunpoint on a criminal.

Dr. Noelani Cunha's uncle dies mysteriously and she sets out to discover what really happened to honor his memory, and arrest his murderer.

On Valentine's Day, Tani and Noelani are held hostage during a convenience store robbery. Also, Five-0 investigates the murder of a Thai diplomat whose wife confesses to the crime, but Danny suspects she's covering for the real killer.

Five-0 investigates a deadly home invasion after an extremely dangerous prisoner escaped from the basement. Max returns to the island with a guest.

McGarrett helps his sister spy on shady neighbors; a ride-share driver and his passenger are murdered; the team teases the youngest members when Junior escorts Tani to a wedding.

Five-0 investigates the murder of a man whose body may hold the key to a 20-year-old case involving a kidnapped girl whose father never stopped looking for her.

Five-0 must locate a teen girl who purchased a gun from a junkie, and discover that the firearm, over the course of decades, has affected all of their lives.