TK Jensen arrives at the police station to meet with Stottlemeyer for a date. Monk notes that several clues and realizes that Stottlemeyer is ready to propose to TK. He tells TK and the others to hide the information, but they all burst into tears when Stottlemeyer comes out. He realizes something is up and Monk quickly admits that they know he's planning to propose. Stottlemeyer tries to propose right then and there but TK tells him to do it later so she can hear what he has to say.
Later, Stottlemeyer is called to a crime scene in the park where a bum was apparently shot and then burned. He believes something is going on and tells Disher to call Monk in, and then goes on his way, singing and dancing.
Later, Disher is at the station practicing a song for the wedding. Natalie is less than impressed. Meanwhile, Monk assures Stottlemeyer that he's fine that TK's first name is Trudy. The captain then asks Monk to be the best man at the wedding. Monk admits he's flattered, apprehensive, and anxious, but agrees to do it. He promises not to lose the ring. TK arrives and disturbed by the photos of the crime scene, but Stottlemeyer admits that it's his job. She then tells Stottlemeyer that Stephanie Briggs, her maid of honor, got arrested for speeding. He agreed to help get her released.
Later, TK and Stottlemeyer meet with Stephanie as she's released. He's asks her why she was speeding and Stephanie says it was an emergency: she had to get to the caterers. Stottlemeyer suggests they have a casual wedding but TK points out that the wedding is for their friends and family. Stephanie offers to check on his tuxedo but Stottlemeyer says it isn't necessary and she bids them farewell.
At home, Monk goes about his everyday life… holding onto the ring the entire time. Natalie asks about the preparations for the bachelor party and notes that he's very excited.
Stottlemeyer and TK come back to his house from a date. She agrees to spend the night but they go inside and discover the house has been ransacked.
A week later, Stephanie and Natalie are going over the seating arrangements with TK and she shows them her wedding dress. Natalie prepares to meet Monk at the crime lab and TK asks her she handle the blood and violence. She admits she's not sure if she can handle being a cop's wife.
At the crime lab, Monk is busy rearranging the mixed flower arrangement when Stottlemeyer calls him over to check out the victim's shoe. Monk is still holding the ring. He tells Disher to be at the bachelor party at six p.m. sharp, and then determines the dead man was tall and bowlegged. Monk finds a thorn that was cut, and a piece of Styrofoam. Stottlemeyer tells them that TK is having second thoughts about the wedding because of the break-in. She made a rule that he can't bring the gun in the house. Monk realizes that the Styrofoam is from a flower display and the killer was a florist.
TK is in the park when someone calls her using a voice scrambler and says he's responsible for the mess, and he might come by when they're at home. Stottlemeyer meets her and promises he'll take care of it and stay with her that night. When he wonders about the bachelor party, TK tells her to go anyway while she goes to her office where she'll be safe. She asks if this will be her life from now on and Stottlemeyer assures her it has never happened before and won't again.
At the bachelor party, Monk orders plain pizza and hands out multiple coasters. Disher asks Stottlemeyer about TK and the captain assures him she'll be okay. Monk then tries out a joke about Stottlemeyer's previous failed relationships, but it doesn't go well. He then hands out the beers: one per person. Stottlemeyer notes there's enough for one of them to get drunk, and they choose Disher. Monk then hands out the selected movie: Bachelor Party. Nobody is particularly happy at the choice. A drunk Disher comes in to tell the captain that someone set his car on fire.
The next day, Stottlemeyer and Disher go over the files and the captain explains that TK freaked out and they stayed at a hotel. There are no witnesses to the burning car incident and no usable evidence. Stottlemeyer wonders why his stalker is playing cat-and-mouse games Disher suggests the brother of a man they put away, but he's deceased. An officer gives them a report on the dead man in the park, and they've learned a florist clerk, Charlie Doyle, has been missing since before the murder. Stottlemeyer tells him to check it out while he tries to save his coming marriage.
Disher, Monk, and Natalie meet with the florist, Joy, who admits it's not like Charlie to disappear. She remembers he wore boots like the murder victim, but explains she paid him off the books. Joy then tries to check Monk's aura and says that it's in a dark place, and tries to pick the best flower for him. Disher asks for a photo of Charlie, but Joy says that he didn't like having photos taken. They check out his work station for fingerprints, and Joy decides that Monk's flower is plastic.
At the church, Stottlemeyer and TK meet with their family members and Stephanie arrives. Meanwhile, Monk wants to walk TK's father down the aisle because they're the same height and it would look cool. Disher confirms that Charlie's fingerprints match those of Martin Kettering, a fugitive from an eco-terrorist group that killed two men. Kettering has been on the run ever since. The priest begins the rehearsal and Monk walks down the aisle with Stephanie. As they go, Stephanie asks Monk if he thinks Stottlemeyer will go through with the wedding. As they get to the aisle, one of the presents explodes and Stottlemeyer realizes that TK is gone. He runs outside, unaware that she's fleeing down a side street in a panic.
Later, Natalie and Stephanie meet with TK, who has called off the wedding. She notes that Stottlemeyer offered to resign, but realizes that he'd be miserable without his job. Stephanie assures her that she's making the right decision. However, Natalie says that she was married to an Air Force pilot, and despite the fact she lost him, she doesn't regret a minute of it.
At his office, Stottlemeyer admits to Monk that it's over, but Monk insists that TK is his answer and he refuses to give up. Stephanie comes in to take back his tuxedo. She tries to assure him he'll be okay. Once she's gone, Stottlemeyer vows to find the man responsible, but Monk realizes Stephanie bought the flowers from the same shop that Kettering worked at… and Kettering disappeared the night that Stephanie was arrested. Stottlemeyer and Monk go outside and ask her a few questions, such as where she was before she met TK. Stottlemeyer accuses her of knowing Kettering and starts to escort her inside. Stephanie takes a gun out of Stottlemeyer's tuxedo and takes Monk hostage, the same gun that was used to kill Kettering. Monk explains what happened: she reinvented her life but went into the flower shop and saw Kettering. Kettering tried to blackmail her so she lured him into the woods, shot him, and burned his body to conceal the evidence. She was pulled over afterward and hid the gun in the garment bag with the tuxedo. Stottlemeyer took the gun up to his office. When she couldn't find the gun, she tried to panic TK into calling off the wedding so she could take the tuxedo back.
TK arrives and says she won't abandon Stottlemeyer. Stephanie tries to take her hostage as well and Stottlemeyer says the gun is unloaded. She fires one shot to demonstrate, and Stottlemeyer explains the clip fell out and she just fired the one shot in the clip. Stephanie is taken away while TK insists on marrying the captain.
Later, Stottlemeyer and TK have their wedding on the beach after all. They manage to pry the ring out of Monk's hand and they give their vows. TK then asks for Leland's wallet and pins his badge on his jacket.