Facing strong pressure by the Justice Department to clean up the Islands, Five-0 conducts simultaneous raids [via split-screen] on illegal activities run by the Kumu, Hawaii's biggest and most diversified mob. The Kumu's godfather is Cappy Pahoa (Manu Tupou). His daughter Kini's new boy friend, Jimmy Rego (Reni Santoni), fresh from San Francisco, has taken charge of the Kumu's protection racket.
To find out who is tipping off Five-0 about his operations, Rego sends two of his boys, Kimo Napaii (Rod Aiu) and Peter Kalua (Brian Liu), to Chinatown to investigate. Suspicion soon falls on the nephew of a restaurant owner, who claims to have recently arrived from San Francisco. When he refuses to pay protection until he see the 'Big Boss," they put him under observation. When he is caught sneaking out to make a phone call, he is taken to Rego who quickly proves that he is not from San Francisco, he's from Five-0. When the man spits in Rego's face, Rego promises that he'll pay for that. The man tells him it was worth it. Shortly thereafter, his body is thrown from a speeding car in front of the lolani Palace, Five-0 headquarters. The dead man is Chin Ho Kelly (Kam Fong).
Vowing to avenge Chin's death, the Five-0 team follows one of his leads to a young restaurant owner who promises to finger the two men who have been pressuring him. However, no sooner have Danno and Duke left the premises than the man is killed by an explosion as he opens a fresh drum of fortune cookies. Witnesses report that the truck delivering the drum belongs to Hawaiian Restaurant Supply, one of Pahoa's legitimate companies. Although McGarrett doesn't believe Pahoa would be dumb enough to use his own truck in a hit, it gives him an opportunity to really apply pressure, including having Pahoa arrested at a cock fight. This really upsets Pahoa who has never been in jail before.
Having checked mainland records, McGarrett is convinced that Rego is behind Chin's death. Visiting Pahoa in jail, he tells him, "I want Jimmy Rego." "He's not mine to give," says Pahoa. McGarrett promises to close him down tight until he does. Released from jail, Pahoa warns Rego to back off. He tells him to take Kini and go to Europe for a long vacation -- now. When Rego resists, Pahoa says, "You can either go first class 747 or in an oil drum in the hold of some freighter." Rego appears to agree, but actually orders his two goons to rub out McGarrett, a plan that fails. The goons are arrested.
When Chin's daughter Suzy (Jean Marie Hon) arrives from the mainland, she renews her acquaintance with Kini (Elissa Dulce Hoopai) and, thus, gets close to Rego. Defying McGarrrett's order to stay out of danger, she searches Rego's room and finds the gun with which her father was killed. With the goons and the gun tied to Rego, Pahoa has had enough. He sends his own men out to eliminate Rego. In a panic, Rego calls Kini and has her plead with her father to spare him.
He reluctantly agrees; but when McGarrett shows up, he stoically gives him Rego's beach house address.
Spotting Five-O's arrival, Rego makes a run for it, firing as he goes. Danno drives Rego along the beach toward Steve, who batters him to the ground at the base of a palm tree, then intimidates him with his gun until Rego is a blubbering wreck. When Danno arrives to do the honors, Steve says, 'Danno, hold it. I want to book this one. I think Chin would have liked that."
NOTE: You will observe some differences between the summary above and the one given by Richard Meyers in his book Murder on the Air (Mysterious Press, NY, NY, 1989), which states:
Chin Ho Kelly was killed by a mad-dog murderer played by Steven Keats. Steve McGarrett ran him to ground at the base of a palm tree on the beach and stuck a gun in his face. Even so, he managed to resist the impulse to become a cold-blooded executioner. As always, he had Dan-o [sic] book Chin Ho's executioner ... "murder one."
Well, not quite. The part about the beach, palm tree and gun in the face are right, but nothing else is. Of course, one could argue about whether Chin Ho's killer was a "mad-dog," but not about who played the part. It was Reni Santoni, not Steven Keats. And Dan-o [sic] didn't book him. It was McGarrett himself. And no one said the magic words "murder one."