Robert Kwon (Soon-Teck Oh) is snooping around the outside of Joan Carter's (Linda Marsh) house -- he cuts the phone line. Inside, Joan hears a noise, wakes up and enters the living room holding a gun. When she sees Kwon, she shoots him, then rushes next door to her neighbor Nancy Warren's (Patricia Herman) with her daughter Annie (Katy Kurtzman) in tow to call her "old friend," Steve McGarrett.
When McGarrett and Kimo arrive, there is no body or blood on the carpet, despite Joan insisting that she shot someone. On the way out, McGarrett talks to Annie who says she was sleeping and didn't hear anything until the sound of the gunfire woke her up. After, Joan and Annie discuss the events which have just transpired. The phone rings, but no one speaks on the other end. It is Kwon.
At the Five-O office, Lori and Kimo tell McGarrett there is no record of any wounded people checking into hospitals, despite the fact the gun was actually fired. Kimo insists that Joan "dreamed the whole thing up." McGarrett reveals that he was at the wedding of Joan and her ex-husband Gary (a former assistant district attorney). Gary and Joan were very much in love, and people were surprised when they later got divorced.
At Joan's house, Gary (Guy Boyd) comes to visit her, having been tipped off by Nancy. Joan is very annoyed, saying she doesn't have time for him. Despite the fact that he says he still loves her, Joan says that "it's over" and that he should let her live her own life. Gary wonders if Joan is capable of looking after Annie, and whether Joan is having another nervous breakdown. Joan kicks Gary out of the house.
Later, after Joan drops Annie off at school, she sees Kwon standing nearby at a gas station across the street looking at her. She attempts to run him over with her car. She screams that she knows him as she is restrained by an attendant from the station.
At the Five-O office, Kwon says he never saw Joan before. Gary demands McGarrett book Kwon, but McGarrett says there is nothing he can do legally, and in fact Joan attacked Kwon. As they leave the Five-O office, McGarrett tells the team to check everything on Kwon. As Gary is helping Joan to her car, she sees him again, but Kwon vanishes before Gary looks in his direction.
Joan visits Nancy at the latter's flower shop and says that she is upset that Nancy told Gary about the incident at her house. (Aside from being Joan's current next door neighbor, Nancy was once Gary's co-worker.)
Five-O discovers that Kwon just got out of jail after serving a five-year stretch. The prosecutor who put him in jail was Gary. When Lori wonders if Kwan is terrorizing Joan to provoke a nervous breakdown, McGarrett says Joan had suffered from such problems a few years ago and spent a year in a private hospital. Despite this, Steve still believes Joan's story about the intruder, based on his cop instinct.
Joan meets her boyfriend Stan Thomas (Wayne Ward) at a restaurant, and he assures Joan that he believes her story. A waiter serves her coffee -- and it's Kwon! Joan leaves, very agitated.
At the Five-O office, Gary wonders why McGarrett let Kwon go. Gary recalls the case against Kwon, who made threats against him in court. Gary wonders if Kwon will go after Annie when he finds out that Gary and Joan are no longer together. When McGarrett suggests that Gary take Annie away, Gary says this isn't possible under the terms of the divorce.
When Joan arrives home from shopping, Annie's two pet birds are dead. Joan calls McGarrett, but when he arrives, both of the birds are alive. Joan faints.
Joan wonders aloud to McGarrett whether she is having another nervous breakdown. McGarrett suggests she lie down, saying "you're tired." Stan arrives, and McGarrett leaves them together.
At the Five-O office, Kimo says that Joan is "over the edge." McGarrett tells him and Lori to find out where the dead birds are from. Lori discovers a pet shop who sold two such birds to Kwon about a week before.
Gary visits Nancy at the flower shop and reminisces about their past relationship. He tells Nancy he appreciates her keeping him informed about what is going on. He gives Nancy a gun to give to Joan to replace the one the police took away after the shooting.
Kwon is dragged to the Five-O office by Kimo and grilled by McGarrett about the parrots. Kwon says his birds died, but he threw them away. McGarrett tells Kwon to stay away from Joan, which prompts Kwon to say that he has served his time, he now has a job at Sea Life Park, and that McGarrett has no right to harass him.
After Kwon leaves, Kimo says that McGarrett should book Kwon, but McGarrett says that Kwon doesn't have the imagination to concoct such an elaborate scheme. Lori and Kimo have looked into the backgrounds of Stan and Nancy -- both are clean.
Nancy gives Joan the gun, and Joan puts it in a desk drawer in her house.
Annie shows up at Sea Life Park. She talks to Kwan saying that "everything's going just fine." Kwan says things aren't going fine for him -- he wants to go for the money.
Gary talks to McGarrett about the messy divorce proceedings he went through with Joan and the prolonged fight over custody of Annie, but says "that was a long time ago." Gary wonders if Kwon is after money like the $100,000 inheritance that Joan's mother left in trust for Annie.
Kwon phones Joan, saying he is going away, and he wants money -- specifically $100,000. He gives her instructions on getting the money from the bank. Annie tells her mother to "give it to him." On the phone to Joan, Kwon threatens Annie. He tells Joan to go to Sea Life Park after she gets the money.
After she takes out the money, the bank tells Gary, and he calls McGarrett who phones Joan, insisting that she stay home. However, when McGarrett arrives at the house, Joan has already left and Annie, who is clutching a popcorn box, says that Joan went to "the lighthouse" on "Diamond Head Road." As McGarrett is on his way there, he flashes on the popcorn box which had Sea Life Park written on it (the location of Kwon's job). He turns around and heads for the park.
Joan meets Kwon by the breeding tank at the park and gives him the money. McGarrett and members of HPD arrive and chase Kwon, who is captured after firing a few shots.
After Gary shows up at the park, McGarrett says that the whole plot was masterminded by Annie, who was upset because she couldn't go to the mainland with her boyfriend. Annie arrives and walks past her mother, which earns her a rebuke from McGarrett. Annie turns on her parents and abuses them for their "mistreatment" of her, but McGarrett tells Annie to cut the crap. After Annie breaks down in tears and is momentarily reconciled with her parents, McGarrett tells Kimo to take her downtown and book her. When Joan protests, McGarrett says it's up to the family court to decide what to do.