Monk and Natalie arrive at Stottlemeyer's office to get some papers signed and finding him talking with his girlfriend Linda over the computer from her bedroom. They are leaving for a vacation in Hawaii on the upcoming weekend and Linda mentions that her partner Sean is showing a house. Sean is showing the house to a couple when a robber bursts in with a shotgun and guns him down, while the couple run away.
The next morning Stottlemeyer meets Linda at her house .where he has a city worker removing a hanging branch and a policeman tow away an illegally parked truck. She gets the call that Sean is dead in Malibu. Sean promises to help her find the killer and sends Monk. The police are interrogating the couple, who wonder why they weren't shot. The wife suggests that the killer was a woman as she was wearing lipstick. They look at the point of entry and it appears that the killer had a key.
Monk talks to Linda who says Sean had a female enemy, Helen Hubbert, who wasn't happy with a house he sold her. However, Monk begins to suspect Linda, noticing she is the same height as the killer, had a key to the house, is getting Sean's client, and uses the same lipstick as the killer. They go to Disher who notes that Linda was talking to Stottlemeyer on the computer and couldn't have possibly been at the crime scene 20 minutes later. When they realize Linda has a motorcycle, they decide to drive across town to see if she could have made it in time. Natalie gets a bike and Monk eventually manages to get on and they're off… until Monk falls off since he won't hold on to Natalie.
Eventually they get going but it takes them over an hour. However, Monk notices flowers at the scene that match the lei she was wearing on the webcam when they saw here from Stottlemeyer's office. They go to give Stottlemeyer the news and he is not happy and believes Monk is jealous.
Stottlemeyer interrogates Helen Hubbert and she admits she hates his guts, and doesn't have an alibi. Monk listens in and Stottlemeyer gets mad again when Monk tries to intervene. Adrian is convinced that the killer had to have an alibi and since Hubbert doesn't have one, she must be innocent. Stottlemeyer admits that Linda is the last chance he has but Monk sticks by his deductions.
Natalie gets Linda to show her a house but Stottlemeyer calls and quickly figures out Monk's absence means he's busy elsewhere. He tells Linda that Monk suspects her and she begs off and heads back home, where Monk is going over the place. He finds a truck rental bill and a bottle of gun oil. Linda arrives and finds him searching the place, and claims the shotgun was stolen. She asks him up to his bedroom to show him the police report and then tries to seduce him. Monk runs from the house in a panic where Natalie picks him up, and he reveals he know how she did it.
At the police station the next day, Disher is throwing a luau party for Stottlemeyer's trip and Linda is in attendance. She claims that Monk was crazy and tried to force her to go to bed with him or he'd frame her. Stottlemeyer is immediately skeptical of the claim that Monk would touch any woman. Natalie arrives alone and asks Stottlemeyer and Linda to go into the captain's office for a surprise present. In the office, Monk is broadcasting over the computer from Linda's bedroom and says he knows how Linda did it. She turns off the computer and appeals to Stottlemeyer to get her out of there, but they can hear the same Hawaiian music from the impound lot outside. They go outside and find the music coming from a rental truck. Inside is Monk sitting in an exact replica of Linda's bedroom. Monk explains that Linda rented the truck and duplicated her bedroom inside. On the night of the murder, she parked the truck near the murder site, talked to Stottlemeyer, then went outside and killed Sean. However, the truck was towed, messing up her plan. Monk also noticed that a pen during her transmission rolled when she set it down, but it didn't roll when he was in her bedroom. On the night of the murder, the truck was on a slant. She appeals to Stottlemeyer who has no choice but to order her arrest.
Stottlemeyer ends up in Hawaii and takes Disher on the second ticket. The captain wonders if Linda ever loved him or if it was a setup from the beginning. Randy misses it and wonders if Linda ever loved Stottlemeyer or if it was a setup from the beginning. Stottlemeyer tosses something into the ocean: an engagement ring.