| Ua malo'o ka wai |
(The Water is Dried Up)
|Season 7, Episode 21|
|Air date||April 7, 2017|
|Written by||Eric Guggenheim|
|Directed by||Bronwen Hughes|
Huikau nā makau a nā lawai'a
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.
- Charles William, Grace Park, Renee Grover and were all mentioned, but did not appear.
- The events from Ike Hanau, Umia Ka Hanu and Malama Ka Po'e were all heavy plot points.
- Jerry Ortega received his Hawaii Five-0 Task Force badge and is an official member.
- Lou Grover testified against his old friend, Clay Maxwel who killed his wife, stole money and tried to kill Grover's family. 
- Steve McGarrett killed 1 person 
- Chin Ho Kelly killed 1 person 
- Yakuza kiiled 4 people
- Michelle Shioma killed 6 people
- Honolulu Police Department killed approximately 15 people
Chin Ho Kelly: Looks like someone gutted these guys.
Danny Williams: I’m sure the birds appreciated that.
Danny Williams: You're a SEAL right. You know how to pick a lock?
Steve McGarrett: No, I know how to ride a C4 charge. Alright, they taught me how to be a soldier, not Houdini.
|Steve McGarrett||Alex O'Loughlin||A former Navy SEAL and the leader of the Hawaii Five-0 Task Force.|
|Danny Williams||Scott Caan||2nd-in-command of the Hawaii Five-0 Task Force and Steve's partner.|
|Chin Ho Kelly||Daniel Dae Kim||A member of the Hawaii Five-0 Task Force, and Kono's cousin.|
|Kono Kalakaua||Grace Park||Youngest member of Hawaii Five-0, and who is Chin's cousin.|
|Jerry Ortega||Jorge Garcia||A conspiracy expert and an associate of the H50 team.|
|Lou Grover||Chi McBride||Former leader of the HPD SWAT, and newest member of H50.|
|Sgt. Duke Lukela||Dennis Chun||Sergeant with the Honolulu Police Department.|
|Dr. Noelani Cunha||Kimee Balmilero||Medical Examiner for the Hawaii Five-0 team.|
|William Grover||Chosen Jacobs||Second born child of Lou Grover and his wife Renee Grover|
- Michelle Krusiec as Michelle Shioma
- Wesley John as Yakuza Soldier
- Christopher Kim as Yakuza Soldier
- Joseph Anderson as Officer Bennett
- Jenson Cheng as Ozaki
- Craig Ng as Matsu
- Thomas Johnson as Richie