The episode begins at a bachelorette party. After the party, the bride-to-be and her friends head to another bar. They run into another car. They then see two men get down from the other car, open the trunk of their car, fire shots and then run away. They are horror struck when they see the dead body in the trunk. Next, Steve arrives to meet Mick Logan, ex-military intelligence. He wants Mick to investigate his mother, Doris. Steve tells him that Doris is a former Government agent. He wants to know what his mother is up to. Steve gets a call. Later, at the HQ, Kono briefs the team about the victim. His name is Thomas Hoapili and he has a daughter, Maggie Hoapili.
The murder weapon is a .45 and Fong is processing it. The car Thomas was found dead in was reported stolen two days ago. Steve analyzes the whole thing and infers that this was an execution. Fong has managed to pull a partial print off the murder weapon; it is Kamekona!! Steve and Danny question Kamekona. Kamekona tells them that Thomas was his cousin and they were very tight. Thomas was the only one who believed in him after Kamekona got out of prison. Thomas had helped him a lot. Kamekona tells them that he could not even think of killing Thomas. He also tells them that he had given Thomas a gun for his protection. Kamekona doesn’t know why Thomas needed a gun. He asked him for help and Kamekona helped his cousin. Steve believes him and asks Kamekona to keep in touch just in case he learns something.
Steve and Danny leave. They wait in the car and moments later, they see Kamekona get into his van and drive off. They follow him. We also see that Kamekona is carrying a gun with him. Next, at the departmental store, Mick follows Doris and Doris realizes that and confronts him. He acts as if he was trying to hit on her. Doris seems convinced and agrees to go on lunch with him. Kono and Ho are talking to Maggie. She doesn’t know about the gun. Ho notices that Thomas had gotten recommendations from HPD. Maggie tells him that Thomas had managed to turn in the guys who tried to rob them last year. Ho thinks that this murder could be revenge. Next, Kamekona pulls up in front of a house.
Steve and Danny confront him. Kamekona tells them that he wasn’t completely forthcoming earlier. He tells them that Thomas told him that Eddie Thorne might be looking for revenge because he had seen Eddie hanging around at the fish market a couple of times. Thomas had put Quinn, Eddie’s brother in prison for trying to rob them. And that is why Thomas wanted the gun. Danny puts Kamekona under a shrimp truck arrest till this clears out. They then go to Eddie’s house and arrest him. Eddie tells them that he was trying to rob Thomas. Some of the tuna could fetch a very good price and that could set him for life. That is why he was following Thomas and making a note of his timings.
Ho arrives and tells them that they need to see something. Ho shows them a video where Thomas is being grabbed by two perps; one male (who is not Eddie as he is too tall) and the other one is a female. They notice that the duo don’t go back into the store to rob anything. This means that this wasn’t a robbery. Steve, checks the time stamp and it is 9:15pm. Thomas was killed around 2:30-2:45 am. He wonders what happened during those five hours in between. Mick and Doris are having wine and Mick tells her that he is on vacation in Hawaii. He is from Ohio and deals in fabrics. Steve calls and Mick tells him that he did not get much on her. Steve tells him to dig deeper. Steve is sure that his mother is running some covert op.
Max tells Steve and Danny that Thomas did put up a good fight before his death. He also tells them that Thomas suffered the injuries and the trauma elsewhere. Kono goes to meet Kamekona. She then shows him the pictures of the suspects. But Kamekona is not able to recognize them because the pictures aren’t clear. He wants to keep them with him and show it around. Kono agrees. Ho calls her and tells her that Maggie lied to them about going to the golf range with her father. He says that the people around told him that they haven’t seen Maggie and Thomas in years. They confront Maggie, but she refuses to speak. They bring her to the precinct and she still doesn’t speak. They then bring in Kamekona and Kamekona convinces her to co-operate and help find Thomas’ killers.
Ho tells her that Thomas was badly beaten up before he was shot. Maggie says that it was impossible to beat up Thomas as he was a Lua master. Lua is a traditional Hawaiian hand to hand combat and only native men were allowed to be trained in this form of martial art. But Thomas wanted to pass on his legacy and so he trained Maggie secretly and made her promise to remain quiet about this. Maggie tells them that Thomas trained around two dozen men. Maggie brings them to the training ground. Ho and Kono talk to Shane, the man who looks after the training along with Thomas. He tells them that Thomas was a nice man and he had no enemies.
Ho tells him that Thomas had defensive wounds on his body. So he needs to check all the students for bruises. At the HQ, Steve tells Danny that the students had nothing to do with the murder. Kamekona arrives and tells them that he got a hit on the female perp; her name is Kat Carrigan. They go to Kat’s house but it is empty. They check her laptop and they find a video where a bald man is beating up Thomas in a duel and there is a huge crowd watching this. The bald guy is Ramsey Pollack who flew in two days back. They learn that he is proficient in six forms of martial arts and is known for conducting illegal underground fights. This is big stake and people put in a lot of money to watch these fights. These fight clubs have no rules and people get killed.
Ho tells them that there have been 26 wire transfers in the past 48 hours and no one is talking about the fight clubs. Pollock wanted to up his performance and so this fight with a Lua master was a hot ticket. They also learn that Pollock transferred half a million into Kat’s account. Since these fights fetch a lot of money, Ho thinks that there is a possibility of a second fight and he also knows who the next opponent will be. He calls Maggie. Maggie answers the call but before she could talk further, she is tased. Later, the team is at the abduction site and the camera footage shows that Kat and Pollock abducted Maggie. Ho tells Steve and Danny that Pollock’s call records indicate that he has been talking to Shane.
Next, Maggie is tied to a chair and Shane arrives to talk to her. He tells her that he gave his life for that school and he still had to live under Thomas’ shadow. He tells her that he told Thomas that they could make a lot of money if they trained outsiders; but Thomas refused to sell out. Shane says that he was left with no choice. They then bring Maggie to the ring (which is an empty swimming pool). Kat is waiting for her and there is a crowd waiting for the fight to begin. Maggie refuses to fight. She is thrown in. The team tracks down Shane’s phone and they get a location. Kat breaks Maggie’s hand. Maggie then decides to fight and Kat is no match for Maggie’s skills.
On seeing that they are about to lose, Shane jumps in to fight Maggie. But Steve arrives and shoots him in his leg. Pollock is arrested and Ho takes Maggie to the hospital. Later, Kamekona arrives to meet Maggie. She assures him that she will be fine. Next, Doris is all dressed up for her date with Mick. Steve is shocked. Doris leaves for her date. On her way out, she tells Steve that if he wanted to know what she was up to, he could have simply asked. The episode ends.