When a woman is murdered in her home, Five-0 learns that one of their own has a deep connection to the victim’s young daughter.

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 must work with rogue MI-6 agent Harry Langford to find a terrorist planning to cause nuclear reactors across Europe to meltdown. Also, McGarrett and Danny ask retired FBI profiler Alicia Brown to help them find their serial killer vigilante.

Five-0 must find McGarrett and Alicia when they are kidnapped by the serial killer they’ve been hunting,

Five-0 must free McGarrett's mother, Doris, when Catherine informs them that she was captured and is about to be executed after attempting to free Wo Fat's imprisoned father. Also, Chin loses his appeal to have Sara's adoption delayed, and she must move to Mexico.

While Danny chaperones Grace’s winter formal, terrorists seize the venue and hold everyone hostage in order to kidnap a diplomat’s son

Five-0 races to Mexico where Chin puts his life on the line after his niece Sara is kidnapped.

The team handles the fallout in Mexico after Chins problems, back on the Island Grover goes undercover and things get hot.

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.

McGarrett risks his life when Five-0 attempts their most dangerous rescue yet of young girls trapped in the sex trafficking ring they have been tracking this year. Also, Kono, deeply affected by the case, makes a life-changing decision.