| Aloha ke kahi I ke kahi |
(We Need One Another)
|Season 4, Episode 1|
|Air date||September 27, 2013|
Aloha, Malama Pono
A'ale Ma'a Wau
H50 face a battle on their hands when members of the terrorist group, NLM storm their headquarters, taking hostages and the stakes are raised further when Catherine is later kidnapped, forcing Steve into a race against the clock to save her while Kono and Adam are jeopardized when their secret location in Hong Kong is left compromised as a result of the hostage crisis.
In response, Steve McGarrett kills all but one of the gunmen, a man named Ricardo Cosi.
After taking Cosi to H50 Headquarters, more men from the NLM storm the building where H50 is located and take everyone there hostage so that they can retrieve Cosi.
Steve and his partner, Danny Williams attempt to hide Cosi but are ultimately forced to surrender when the main leader of the NLM team threatens to kill the hostages if Steve and Danny don't co-operate.
Steve and Danny relent, bringing Cosi with them and are taken prisoner but in a shocking development, Cosi is later shot dead and the terrorists knowingly surrender.
As the terrorists are being escorted to jail, Steve learns that the NLM's overall leader, El Condor has kidnapped Steve's girlfriend, Catherine Rollins and is holding her hostage.
To save her, Steve has to break the NLM members out of custody which leaves him at loggerheads with Lou Grover, the head of the Honolulu Police Department's SWAT team.
Despite that, Steve and Grover work together to track the NLM to a stadium where they intend to escape via a stolen helicopter while they later destroy the Camaro.
All the terrorists are killed in a crash before they can escape.
Steve secretly obtains Wo Fat's blood and has Max Bergman run a blood test as Steve has a strong suspicion that Wo Fat could be his half-brother.
Adam Charles AKA "Toast" later analyses the footage from the destroyed tablet table and the team discover that during the siege the NLM found Adam and Kono's location in Zhejiang, China and sold it to the Yakuza, prompting Chin to call Kono and warn her while also stating that she and Adam should leave right away.
Kono and Adam attempt to do so, only to discover that Yazuka members are already at their hideout, ending the episode in a cliffhanger.
- Captain Lou Grover, the head of the Honolulu Police Department's SWAT is introduced for the first time.
- Chin Ho Kelly discovered that the NLM found Adam Noshimuri and Kono's location in Zhejiang, China and sold it to the Yakuza and they have been compromised.
|Alex O'Loughlin||A Navy SEAL and the leader of the Hawaii Five-0 Task Force for Governor Sam Denning.|
|Scott Caan||Second-in-command of the Hawaii Five-0 Task Force and also Steve's partner.|
Chin Ho Kelly
|Daniel Dae Kim||A member of the Hawaii Five-0 Task Force.|
|Grace Park||A member of the Hawaii Five-0 Task Force who graduated from the HPD Police Academy and who is also Chin's cousin.|
|Dr. Max Bergman||Masi Oka||Chief Medical Examiner for the Hawaii Five-0 team.|
|Lieutenant Catherine Rollins||Michelle Borth||A Lieutenant in the US Navy and Steve's girlfriend.|
|Wo Fat||Mark Dacascos||A crime boss targeting Shelburne who is Steve's mother, Doris.|
|Adam Noshimuri||Ian Anthony Dale||The son Yakuza gangster, Hiro Noshimuri, and Kono's husband.|
|Kamekona||Teila Tuli||An associate of the H50 team, and owner of Wailoa Shave Ice|
|Adam Charles||Martin Starr||A hacker.|
|Lou Grover||Chi McBride||Captain of the HPD SWAT team.|
|Sgt. Duke Lukela||Dennis Chun||Sergeant with the Honolulu Police Department.|
|Dr. Gabrielle Asano||Autumn Reeser||A scientist and Danny Williams's girlfriend.|
|El Condor||Nestor Serrano||The NLM's leader whose real name is Esteban Luna.|
|Flora||Martha Higareda||A terrorist with the NLM.|
|Ricardo Cosi||Louis Carazo||A member of the NLM and the nephew of the group's leader, Esteban Luna AKA "El Condor".|
|Juan||Luis Espinoza||A member of the NLM.|
|OWP 4||Eddie J. Fernandez||A member of the NLM.|
|Pua Kai||Shawn Anthony Thomsen||A recruit with Honolulu Police Department.|
|Tomas||Vancamp Popese||A man who appears in the episode.|
|Alejandro||Charlie Compuesto||A man who appears in the episode.|
|Terrorist||Henry Ian Cusick||The leader of the NLM group who storm the Aliiolani Hale, triggering the hostage crisis.|
|Aloha ke kahi I ke kahi ♦ A'ale Ma'a Wau ♦ Ka 'oia'i'o ma loko ♦ A ia la aku ♦ Kupu'eu ♦ Kupouli 'la ♦ [Ua Nalohia ♦ Akanahe |
♦ Ha'uoli La Ho'omoaika'i ♦ Ho'onani Makuakane ♦ Pukana ♦ O kela me keia manawa ♦ Hana Lokomaika'i ♦ Na Hala a ka makua ♦ Pale'la ♦ Hoku Welowelo ♦ Ma lalo o ka ili ♦ Ho'i Hou ♦ Ku I Ka Pili Koko ♦ Pe'epe'e Kanaka ♦ Makani 'Olu a Holo Malie ♦ O ka Pili'Ohana ka 'Oi