Monk, Stottlemeyer, Disher, and Natalie confront Evan Gildea, a sculptor who Monk believes killed his wife Nancy. Monk begins to explain how Gildea used a two-ton block of marble as his alibi. However, lawyer Harrison Powell arrives, tells Gildea not to say anything, and offers his services as the man's lawyer,
A few months later, Monk and the others arrive to testify at Gildea's murder trial. D.A. Charles Friedken tells them to be careful what they say because Powell can be ruthless. On the witness stand, Stottlemeyer testifies that the police received word that Nancy Gildea's was murdered in her home in San Francisco at approximately 10 p.m.. The initial indications were that she found a thief breaking in and he beat her to death with a piece of sculpture. However, when Monk arrives he notices two discrepancies. First, the hole the thief made in the door was too small for an adult human hand.
In the hallway outside, Disher notices that his former Little Brother, Rudy Smith, is sitting on a bench. He goes over to talk, figuring that Rudy is working to become a lawyer. However, a policeman arrives to take Rudy away: he's been charged with Murder One in the death of Mrs. Paddock, a clerk at an auto-parts store.
Stottlemeyer explains that the second clue Monk discovered was that the thief walked away from Nancy Gildea to pick up a piece of sculpture that didn't belong to her husband, Evan. Monk concluded that Gildea was the killer and didn't want to damage his own art. Powell cross-examines and forces Stottlemeyer to admit that the thief could have simply moved during the fight, and that neither Stottlemeyer nor Monk could absolutely testify how the fight occurred.
Disher returns and explains to Monk and Natalie that he feels responsible for Rudy because he promised the boy's grandmother that he'd look out for him. They're surprised to see Stottlemeyer, stunned and covered in sweat, stagger out of the courtroom. He warns Monk to be careful but the detective confidently walks into the courtroom and takes the witness stand. He testifies that he accompanied the police to Evan Gildea's studio in Santa Barbara. Unfortunately for Monk, Gildea was working on a nude sculpture and he couldn't bring himself to look at it. Gildea told them that he received the two-ton block of marble the previous day, spent all night working on it, and just completed it the next morning. Monk doesn't believe it but on cross-exam, Powell gets him to admit that he never actually looked at the statue. Powell has it brought in and Monk still can't look at it.
Disher goes to the lockup to meet with Rudy, who insists that he left the clerk alive after he took the money and ripped her gold necklace off. He thinks there was someone in the store but can't remember for sure if they were there or what they looked like. Disher shows Rudy their friendship bracelets and reminds Rudy that they promised never to lie to each other. He has Rudy put it on and Rudy promises that he's telling the truth.
Powell waits patiently in the courtroom while Monk fixes the microphone support. Once he's done, Powell notes that Gildea claimed that he received the block of marble and finished the statue the next morning. Art experts have confirmed that it would have taken Gildea all night to finish it, meaning he couldn't have left his studio. Monk testifies that when they went to the studio, he spotted an electric clock that was 20 minutes a slow and a half-melted popsicle was in the freezer. From that, Monk deduced that Gildea had used a jackhammer for 20 minutes, using all the studios power. The sculptor carved his nude sculpture in advance, had the block delivered, and then used the jackhammer to reduce it to gravel and scatter it on his driveway.
Powell begins to hammer Monk on his cross-examination, and Natalie objects. Powell turns to her and has her identify herself as Monk's assistant, and that the formerly had a nurse. He pursues that line of questioning and asks Monk why he needed a nurse. The detective admits that he has a breakdown ten years ago after his wife death. Powell questions Monk's competence and has the gravel brought in. When Powell notes that the pieces should fit into the shape of a block, Monk desperately tries to put them together to recreate the block.
The jury finds Gildea innocent and he leaves the courthouse, boasting that justice was served. A cocky Powell reminds Monk and the others that due to double jeopardy, Gildea can't be charged with his wife's murder no matter what they might find against him. The sculptor departs and Monk notices that one of his taillights is dimmer than the other.
As Powell promotes his new book, Undefeated, on the talk shows, Monk goes to see Dr. Bell. The detective is ready to quit, concerned that any murderer he catches could get free just by hiring Powell. Bell tells him about his time in college when he ran up against a pitcher he couldn't get a hit off of, and how he finally figured out the pitcher's tell. Monk doesn't see the point and tells Dr. Bell that he's quitting.
Back at his apartment, Monk is packing away his files when Natalie and Disher arrive. They have a case for him: figure out who killed the auto-parts clerk and clear Rudy's name. Monk notes that Rudy confessed to the robbery, placing him at the scene, and that it looks helpless. Disher and Natalie insist that they believe in him and Monk reluctantly agrees. They go to the auto-parts store and Monk divides his time between looking around and imagining how Powell would demolish his testimony. However, Monk finally concludes that the murder wasn't pre-meditated. He also sees a security camera on the ceiling. Disher explains that the thief took the security tape and Monk realizes that Rudy wasn't tall enough to reach the VCR. Finally, Monk makes a surprising deduction: the clerk's murder took place at 10 p.m. When Disher and Natalie wonder how he figured it out, Monk goes outside and searches a nearby alleyway to find the evidence he knows is there: a broken taillight bulb.
Stottlemeyer brings Gildea in for questioning and explains that he's there for the murder of the clerk, Mrs. Paddock. Rudy is in the next room watching through the mirror but admits that he can't remember if Gildea was in the store. Monk is with Stottlemeyer and explains what happened: Gildea set up his alibi with the sculpture just as Monk claimed. Just before 10 p.m., Gildea drove to San Francisco and killed his wife, making it look like an interrupted robbery. However, as he drove away from his house, the taillight on his car went out. Worried the police would see it and pull him over, ruining his alibi, Gildea went to the nearby auto-parts store and bought a taillight. Rudy picked the wrong moment to rob the store, coming in and taking the money and the clerk's necklace. After he left, the clerk assured Gildea that the security camera captured everything and the sculptor had no choice but to kill her with a tire iron and take the tape to preserve his alibi.
Powell arrives and makes light of their new theory, insisting they have no proof. Stottlemeyer admits it's true but insists that the truth will come out. As Powell leaves with Gildea, Rudy sees him. Gildea accuse him of being a dope-smoking chain-snatching little punk. Monk realizes that Gildea has provided them with the evidence they need to convict him. The police never released the information that the clerk's chain was stolen. Only the killer could have known that Rudy took the necklace. Stottlemeyer arrests Gildea while Powell mocks Monk, noting that he doesn't have a chance against him. His confidence restored, Monk tells a puzzled Powell that he knows what his tell is now and the lawyer won't catch him out twice. As Powell leaves, Monk loses his confidence and begins to panic.
At the new trail, Gildea is found guilty of Paddock's murder after Monk supplies the vital testimony. Powell leaves the court, his perfect record ruined, and he tells Monk to say it. Monk asks him how it feels. As the lawyer leaves, Disher lets them know that Rudy has been remanded into his custody and will be working at the station as community service. Monk turns back to Natalie, who says that he did great and didn't even have to adjust the microphone stand. She and Monk go out of the courtroom... and then Monk returns to adjust the microphone.