|Kupu'eu (Fallen Hero)|
|Season 4, Episode 5|
|Air date||October 25, 2013|
A ia la aku
Kupu'eu (Fallen Hero) is the 5th episode of Season 4 of the 2010 remake version of Hawaii Five-0.
A routine surveillance job for Catherine and Billy ends in tragedy and sets the H50 team on a search for the killer while in Hong Kong, Adam considers making the ultimate sacrifice to save Kono.
On a routine assignment, Catherine and Billy witness a hit man killing their subject, John Cutler, and wounds the two, with Billy later dying in hospital from injuries sustained in the gunfight while Catherine survives albeit with an injured left arm.
Five-0 return to the house to find it had been cleaned out of any evidence.
After finding Cutler's body in his second car, the team learns from his encrypted laptop that he was spying on his wife's security company, on orders from a rival company.
Five-0 realizes that the company's CEO was responsible for cleaning up the scene, but still agrees to give them all the evidence they gathered although the evidence is later discovered to have been contaminated, further complicating the investigation.
Five-0 discover that Billy wounded the hit man, Jason Kroll.
They find him, but he dies before he can reveal who hired him. Catherine finds he was hired by someone at the office of Abbie Maxwell, the mistress Cutler had an affair with. Her receptionist admits he ordered the killing due to his love for her.
Meanwhile, McGarrett asks Joe White (Terry O'Quinn) to track down Doris, only to learn that his mother is active with the CIA again.
In Hong Kong, Adam allows himself to be captured for Kono's safety. The team later say goodbye to Billy who is buried with full military honors.
|Alex O'Loughlin||A Navy SEAL and leader of the Hawaii Five-0 Task Force.|
|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.|
|Grace Park||Youngest member of the Hawaii Five-0 Task Force, and cousin of Chin.|
|Dr. Max Bergman||Masi Oka||Chief Medical Examiner for the Hawaii Five-0 team.|
|Catherine Rollins||Michelle Borth||An Ex-Navy Lieutenant and Steve's on-off girlfriend.|
|Billy Harrington||Justin Bruening||A Lieutenant Commander with the US Navy. A routine assignment he and Catherine are conducting goes horribly wrong|
|Adam Noshimuri||Ian Anthony Dale||Kono's boyfriend.|
|Abbey Maxwell||Lacey Beeman||A woman who appeared in the previous episode.|
|Joe White||Terry O'Quinn||Steve's mentor.|
|Sergeant Duke Lukela||Dennis Chun||A Sergeant with the Honolulu Police Department.|
|Sandra Cutler||Monica Lacy||A woman who appeared in the previous episode.|
|Lee Benner||Larry Poindexter|
|Andrew Burns||Logan Fahey|
|Tom Harrington||Thomas Allen|
|John Cutler||Paul Bauer|
|Jason Kroll||John Mark Harmon|