At the California Lotto show, Marissa Kessler, the Gold Rush Lotto Girl, announces the numbers. Later, she runs outside and a man chases her. She gets to her car but the man shatters the window and she's forced to get out. She climbs over a gate but the man catches and kills her.
Monk is called to the crime scene and notices something wrong: it was no random mugging. He notes the victim was stabbed twice in three different places, with a pair of scissors. Monk figures she met someone inside the station and the killer grabbed a pair of scissors and chased her outside. He finds metallic paint on the victim's fingerprints. Officer Kelton asks for his autograph for a nephew, and Natalie is obliged to kneel over to provide a flat surface. Meanwhile, Stottlemeyer discovers that Disher is trying to come up with "zingers" for describing crime scenes. Disher's angry when Kelton comes up with the same line. Meanwhile, the station manager Stan Lawrence notices Natalie and is charmed with her, and suggests she fill in as the new Lotto Girl. Monk is less than thrilled but reluctantly gives in.
That night Natalie nervously prepares for her first performance while Stottlemeyer determines that supposedly no one was in the station. Monk admits it was fun… one time. Lawrence congratulates her on her job, and the fact that people are calling in. He offers her a full-time job and Natalie accepts. Monk is less than thrilled.
Natalie is part of a new promotion campaign and is occupied with her new job while Monk tries to solve Kessler's murder. He discovers that a Malcolm O'Dwyer was an obsessed fan and sent lots of letters to her. Meanwhile, fans are approaching Natalie in the streets. Stottlemeyer and Disher talk to O'Dwyer who is clearly obsessed with the entire cast and crew of the Lotto show, and even puts out a Lotto newsletter. When he talks about his philosophy of picking winning numbers, Stottlemeyer thinks it's time to leave. Monk arrives while Natalie signs autographs downstairs. Stottlemeyer gets him to admit that it's driving him crazy.
Natalie starts to take over on the set and get a swelled-head despite Lawrence trying to convince her it's about the numbers. As she trips over some cables, she tries to yank them out and the sound engineer, Billy Logan, snaps at her. Lawrence fires Billy for his attitude and Natalie backs down, but it's too late. Meanwhile, Monk talks to Dr. Bell who says that it's natural to become somewhat of a diva. The Doctor notes that Monk feels that he's losing a friend but Monk thinks she's insulting him. He's putting killers behind bars while Natalie reads number. He thinks Natalie is changing, and got the sound guy fired.
Billy goes to see O'Dwyer and notices he's been taking pictures of him. When Dwyer goes for his notepad, Billy takes a baseball bat and knocks him unconscious, then takes his photos.
Monk is called to the new crime scene, where O'Dwyer apparently jumped out the window to his death. There's a suicide note but Monk doesn't believe it's suicide. He finds a contact lens case with only one lens. When Monk gets liquid on his face and needs a wipe, he's reminded that Natalie isn't there for him. He goes outside to find Natalie signing autographs. She tries to introduce Monk but her fans aren't interested in him. He tries to perform for the crowd to get some attention but it doesn't go well. Stottlemeyer finds the other lens and they realize that nobody commits suicide with only one lens. When Natalie gets mad at him, he tells her to choose and she quits.
Later, Stottlemeyer is at the gym talking to Monk on the phone. As he leaves, Billy breaks into his locker and substitutes Stottlemeyer's lotto tickets with some of his own. That night, Monk is in Stottlemeyer's office mourning his loss as they watch TV. Stottlemeyer discovers that he has the winning numbers and won $212 million. As he announces that he plans to quit his job, Monk again notes that everyone leaves him.
Monk is at home eating supper alone when Natalie arrives and says she had nowhere else to go. She has him turn on the TV where the news is announcing that there were two winners, but the Lottery Commissioner suspended the payment after it was discovered Natalie worked with Stottlemeyer. Further, they checked the equipment and discovered that it was rigged, and Natalie will be going to jail for fraud. She asks for his help and they go to the studio the next morning to see the evidence. The commissioner reveals they received an anonymous tip to check out the tape. They checked the number balls and determined they were weighted to come up in a pre-determined fashion. It turns out the numbers were painted with metallic paint, and a magnet in the microphone pulled them up. Monk examines the crime scene and asks what happened to the other winner, Eugene Maddox. Maddox has agreed not to sue in return for a settlement. Monk spots a cap and realizes what happened.
Monk and the others go to confront Billy at a hotel where he's relaxing with Maddox. They try to deny knowing each other but it turns out they've worked on five movies before. The cap had the same logo that was on Eugene's jacket during the press conference. Kessler discovered Billy rigging the equipment and got the metallic paint on her fingernails. When Billy got fired, he lost his security pass and couldn't get back in. Since Billy couldn't turn the magnet off, and the same numbers would have kept coming up, he had to reveal the scheme and frame Stottlemeyer, giving him the same numbers. He killed Billy when he discovered the fanatic had a photo of Billy and Maddox together.
Later, reunited, Monk and Natalie discuss who Garfunkel is. Monk isn't sure…