A tricked-out Harley roars down a middle-class neighborhood street and pulls into a driveway. Dennis Kingsley, a neighbor in his late 30's, stares at the biker as he dismounts. The biker, also in his 30's, stares back. Denny turns away and carries his bag of groceries into his house.
He walks into his kitchen and unloads his groceries so that each label aligns forward. He's borderline OCD. He removes his shoes, puts on slippers and a silk dressing gown, before opening a door that leads down into a pitch black basement. He descends.
Denny enters a room of complete Victorian opulence. A fake fireplace is framed by red brick, late 19th century London artifacts line shelves and desks, and everything is completely immaculate.
He pours himself a snifter of brandy before picking up a violin and playing a melancholic melody.
Some time later, Denny is slumped in his chair in front of the fireplace with a gunshot hole through his head. There are blood, brains and skull fragments on the side table and floor.
Grissom, Brass and Greg Sanders are in the room investigating. Grissom notices the Deerstalker cap, violin, Meerschaum pipe and Persian slipper with tobacco in the toe. He realizes that the room is a recreation of 221-B Baker Street, the home of Sherlock Holmes.
Greg is asked what he thinks as this is his final proficiency test. Greg mentions that the victim is in front of a "fire" in a relaxed position. Powder burns around the entry wound suggest that he shot himself.
Brass asks if it is a suicide, where is the weapon? Greg replies that family or friends sometimes move the weapon to make it appear to be murder in order to avoid the suicide stigma. Brass informs him that it appears Denny lived alone and it was his neighbor who reported the shot.
Brass questions the next door neighbor--the biker--and finds out he's a mortgage broker, in spite of his Hells Angels' appearance.
The CSIs see three costumed people approaching the crime scene. "Dr. Watson," (Nelson Oakes), "Professor Moriarty," (Josh Frost) and "Irene Adler," (Kay Marquette). Both Oakes and Marquette smoke Meerschaum pipes.
The three costumed friends at first think that the crime scene is a setup and remain in character, not realizing the reality. Then they see Denny Kingsley's dead body being wheeled away on a gurney.
Greg finds a bloody, misshapen bullet on the floor and tells Sara Sidle that it's consistent with a revolver, a Colt .45. Sara finds an antique hypodermic case and inside a glass syringe with some drops of clear liquid inside.
Outside, Watson, Moriarty and Adler tell the CSIs that they meet every Thursday night to discuss the Holmes text and cases. Denny said at the last meeting that he was going to make tonight's gathering special. It was to be the final meeting of their society. Grissom asks for their fingerprints and Frost asks if they think Denny's death is more than suicide. Brass tells Frost to drop the accent and he says he can't, he's English.
Inside the 221B Baker Street replica room, Greg finds a small clump of ashes and a tiny opalescent chip. Sara sees that the jamb and latch around the back door is freshly distressed. She finds Denny's computer in the kitchen and sees that he had a long list of unopened emails. She also finds a photo of Denny with a woman and young girl.
Sara tells Greg she found signs of forced entry and that Denny appeared to have a family at one time. Greg shows her a copy of "The Hound of the Baskervilles" with fresh blood stains on the page ends, which doesn't match the blood splatter from the gunshot.
Warrick and Nick are on a rural road investigating a body in the driver's seat of a Jeep CJ with a roll bar top that went off of a hairpin turn and straight down an embankment.
Detective Cavaliere tells them that Nevada Power reported the accident. The driver is Cory DeMayo, age 25. There are no skid marks on the road and no signs that he tried to brake. The key is in the ignition, but the motor is not running. Warrick finds a half-burnt joint in the passenger door. They find no cash or credit cards in the victim's wallet.
Greg informs Dr. Robbins that Denny Kingsley had cocaine metabolites in his urine, B-E level of five hundred nanograms per M-L. Robbins says that levels that high are found only in chronic users. Sara points out Denny's track marks on his arm. Greg notes that there was morphine in his blood and the syringe, not cocaine. The morphine would have incapacitated him in seconds, giving him little time to put away the syringe, pick up a gun and shoot himself in the head.
Detective Cavaliere asks Lyle Dickson when was the last time he saw Corey. He said they were "kickin' it" by Lake Mead. There is a bruise on Lyle's forehead, which he claimed he got from windsurfing.
Warrick tells Lyle that he thinks that he and Corey got stoned and Corey lost control of the Jeep. They ran down the embankment and Lyle banged his head against the dash. Then Lyle took Corey's wallet and emptied it before leaving him there to die. Lyle admits that they smoked pot at Lake Mead, but then Corey took off.
Hodges examines the opalescent fragment that Greg gave him and tells him that it is mother-of-pearl. Hodges also ID'd the ash sample from the floor and found it to be "Perique" tobacco, grown only in St. James Parish, Louisiana. The tobacco found in the victim's slipper is shag tobacco, which is what Sherlock Holmes smoked.
Brass is approached by a cocktail waitress in a dive bar. Brass suddenly realizes that the waitress is Kay Marquette ("Irene Adler")--he didn't recognize her out of her period costume. When Brass asks her for her Meerschaum pipe, she retrieves it for him from her purse. Sara Sidle approaches Nelson Oakes ("Watson") who is in a private security uniform at a hospital. She asks for his Meerschaum pipe and he tells her that it's at home. Sara tells him that she has a warrant and his boss knows about the investigation.
Sara notices a spray of dark drops on the side of Oakes' shoes. He was wearing them the night of the murder.
In the Coroner's Office, Dr. Robbins tells Nick that Corey was physically fit and that the contusion to his head was superficial. Dr. Robbins can't give the CSIs a cause of death.
Nick and Warrick examine the Jeep, finding that the brakes work and that it had gas. However, all the gauges are off on the instrument panel.
Catherine Willows is at her desk when she is approached by Conrad Ecklie. When Warrick and Nick enter, Ecklie asks how their "surfer dude" case is coming along. They say that even though there are no signs of foul play, something doesn't seem right. Ecklie tells them to put the case to bed. After Ecklie leaves, Catherine tells Nick and Warrick to get an answer.
Greg swabs the dark drops on "Watson's" shoe and the pheno turns pink, indicating a presence of blood. Hodges processes the pipes collected from "Watson" and "Irene Adler." He places a pipe under a fume hood and attaches a vacuum to the mouthpiece. He takes the burnt tobacco, adds a few drops of methanol, and mixes it in a vortexer. He withdraws some liquid and runs it through the GCMS.
Brass interrogates Nelson Oakes ("Watson"), implying that if Denny wasn't Sherlock then Oakes could be, instead of playing Watson. Oakes claims he didn't kill Denny as they were friends. Denny was going back to his wife.
Brass presses him, saying that Oakes went to Denny's house, shot him, left, and then came back later with his friends, pretending nothing happened. Denny's blood was on Oakes's shoes and tobacco ash from his pipe was on the carpet next to the body. Oakes continues to proclaim his innocence.
Sara tells Greg that DNA from "Watson's" shoe matches the victim. Greg points out that the blood drops aren't uniform; some are clotted red cells while other are pure serum. Someone took up some of the victim's blood with a plastic syringe and then sprayed it on his shoe. Someone is trying to frame Oakes.
In the A/V Lab, Archie shows Greg and Sara that Denny Kingsley was getting rid of his entire collection of Sherlock memorabilia on an eBay type auction site. One of the items is a perfect mother-of-pearl handled Colt .45 in perfect condition, without any chips. They also find "The Hound of the Baskervilles" book in pristine condition, without bloodstains on its edges. The bidder on the book is named Reichenback from Henderson, NV. Reichenbach Falls is where Professor Moriarty killed Sherlock Holmes.
Josh Frost, aka "Moriarty," is a short-order cook and stands over a grill as Sara and Greg question him. He admits to wanting the 1902 First British Edition of "The Hound of the Baskervilles," as he is a doctoral candidate in English History.
Frost has a paper cut on his hand, which he admits came from a confrontation with Denny. Denny abruptly took back his book from Frost when he couldn't pay him what it was worth. Frost says he admits to having stopped by Denny's house earlier that evening, but he didn't kill him. He would have taken the book if he had.
Nick and Warrick examine the Jeep. Nick finds a blown fuse and fried wiring, and Warrick finds a burn mark on the roll bar and another burn on the undercarriage. They go back out to the scene to check it out.
Warrick and Nick are on the rural road where Corey died. They realize that a downed electrical line would have been a high voltage source that could have burned the Jeep's roll bar. Then they find a metal road marker bent in the direction Corey's car was driving. The marker would have grounded the Jeep, completing the circuit and electrocuting the car.
Greg finds reddish material on the mother-of-pearl chip. He examines it, placing it on a glass microscope slide and then looking at it under a polarized light microscope.
Grissom and Greg go back to the crime scene, the 221B Baker Street replica room. The red clay bricks around the fireplace are real and there is a nick on the brick wall in the back. Greg sticks his head into the fireplace and looking up, he finds the Colt .45, dangling from a loop of surgical tubing tied around a piece of metal.
In the CSI Layout Room, Greg tells Sara that Denny ran a loop of surgical tubing through the gun, secured inside of the chimney. He took a shot of morphine and then shot himself. The gun fell from his hand and then rocketed towards the hearth, hitting the brick, chipping the mother-of-pearl handle, before hitting the back of the firebox and being yanked up into the chimney.
Why would Denny want to frame Oakes? However, figuring out motive is not part of a CSI's job, so Sara tells Greg to write it up and give Grissom the report.
Nick and Warrick apply plaster bandages to a full-size dummy. They make a "mummy" mold and then pour ballistic gelatin into it. They remove the mold and have made a "Gelatin Man." They place copper plates with wires onto Gelatin Man and lead wires from the plates to an ammeter.
Catherine asks them what they are doing and that ballistic gel costs a lot. They tell her they connected the Jeep up to a power source and want to measure the voltage through Gelatin Man. She tells them they will need a reading of at least six milliamps to prove their theory.
They run the experiment and the ammeter registers nothing. They decide to dress up Gelatin Man in clothes. They run a charge through the car again and this time the voltage runs through Gelatin Man's watch and exits his rivet on his shorts. The ammeter registers way above six.
The CSIs have proved that Corey's heart was stopped cold by the shock when the wires contacted his roll bar and then he was grounded when the car hit the road marker.
Ecklie accosts Catherine, telling her that he thought the Corey Demayo case was closed. He wonders if he made a mistake in promoting her. She retorts that he should have given her the Day Shift.
Grissom asks Greg questions about his report. According to the autopsy, Denny was a long-time cocaine abuser, but the syringe he was injected with was filled with morphine. Someone could have switched his coke with morphine.
Greg tells Grissom in the Layout Room that none of the suspects had been prescribed morphine. Grissom uses a scalpel to open up the surgical tube found at the crime scene. He finds tiny leaves of unburned tobacco.
Brass interrogates Kay Marquette (aka "Irene Adler) and asks her if she likes her life. He knows her mother has end-stage cancer. The Sherlock Holmes club was the one bright spot in her life. She admits that it was the only place where no one was grabbing at her breasts or bottom.
Brass tells Kay that he thinks that Denny's breaking up of the Sherlock club must have been more than a disappointment for her. Brass tells her that her blend of tobacco is Cavendish. She doesn't answer.
He decides to lay it out for her. She broke into Denny's house, replaced his cocaine with morphine and when he dozed off, she picked up his gun, put it in his right hand, put the gun to his temple and then shot him. She rigged the gun afterwards with the tubing and it went up the chimney. Then she dropped Watson's tobacco ash, scooped up blood to put on his shoes.
Kay says that it was Oakes' ("Watson") fault as he convinced Denny to give it all up. That is why she framed him. Denny would have wanted his death to be a "puzzle." Greg goes into Grissom's office and suddenly the lights go on. Gelatin Man is seated in Grissom's seat with a big sign that states "You Passed!" on it. Cheers break out and Grissom, Sara, Catherine, Warrick and Nick congratulate him.
Ecklie comes in, congratulates Greg and then breaks up the party. Greg catches up with Grissom and tells him he doesn't understand why he passed since he got the wrong guy, wrong death.
Grissom tells Greg that what was important was that when he collected the evidence and felt that he was missing something, he went back and found it. That is the job of a CSI.