The team looks into a story involving buried treasure from centuries ago and a killer using a stolen painting as a map. The morning after their wedding, Gabriel kidnaps Adam and Kono.

The team go back to school when a college professor is murdered, with Danny posing as the professor's replacement.

The bodies of two serial killers are found with chess pieces in their mouths, so the team hunt for the vigilante as fear grows that tourists aren't safe in Hawaii.

Adam is kidnapped and forced to torture one of Gabriel's men; a wealthy recluse is discovered dead in a field, along with $1 million in counterfeit notes.

McGarrett and Danny go undercover as drug pilots to stop a meth epidemic on the island. But when McGarrett is seriously wounded, Danny is forced to break cover and land the plane.

When a promising local boxer's brother is murdered, an outspoken rival instantly moves to the top of the suspects list.

As Tough Mudder approaches, the team investigates a stunt biker gang after a killer escapes by jumping across roofs on his motorcycle.

Danny and McGarrett attempt to solve their partnership problems with a couples retreat in Maui; Kamekona cannot escape his past.

Five-0 join the bloody trail of a serial killer inspired by Frankenstein; Jerry calls the team when an armed gang raid a blood bank.

The team investigate the weapon used in the murder of a scuba diver. Analysing the weapon found on the ocean floor they realise it was used in another recent murder. McGarrett prepares to propose to Catherine.

A body discovered off the coast of Oahu leads Five-0 to a deadly slave trade business, operating from a fishing vessel.

Five-0 investigate the theft of an advanced piece of military technology. Jerry helps his sister with another important mission.

When a serial killer kidnaps Alicia and McGarrett, the rest of the team must race against the clock to find them.

While Max prepares to say his goodbyes, the team investigate a murder during a police convention on the island.

When the task force's long-time informant is accused of murder, McGarrett brings in an old friend to defend him.

The team tries to follow a truck in a dangerous chase involving a sex-trafficking ring, hoping to rescue the young girls who have been kidnapped; Kono makes a big decision.

Chin gets kidnapped and ends up in serious danger of being executed. The team must find and rescue him before it's too late.

The team are joined by an FBI profiler in the hunt for a killer after she finds a dead body in her bed.

Steve McGarret, a decorated Naval officer, returns to Hawaii to investigate his father's murder and is asked to head up an elite police task force.

Steve McGarrett and the team investigate a double murder. They also revisit their Valentine's Day disasters.