Elementary Wiki
Elementary Wiki


Main cast[]

Featured cast[]


"A correct proof would essentially render all modern encryption obsolete."
— Linus Roe
Mugger Benny Charles holds up a man and then hits him with his knife. Counting the man's cash, Charles walks through an alley and hears a gun shot and witnesses a man being shot in a home. The murderer comes out of the house and shoots Charles as well. The next day, Watson visits the grave of Gerald Castoro, the man she accidentally killed during an operation. His son Joey arrives and presses her to have coffee with him. Having heard about Charles' shooting on his police scanner, Holmes shows up at the crime scene even though Detective Bell texted that he wasn't needed. They view the body of Felix Soto, a math tutor, on his living room floor. Bell indicates that Charles is in a coma in hospital. They both notice that one of Soto's rooms is completely empty. Holmes smells the walls and asks a confused Bell to find a black light. Holmes finds a stand-up lamp with one and once the blinds are drawn, he turns the light on to reveal math equations written on the walls.

S02E02-Joey and Watson
I liked him. He was a good man.
At a diner, Joey congratulates Joan on being a detective and she learns that he's dropped out of university, despite his father wanting him to become an engineer. (♫ Eric Doherty - Lightning Rod ♫) He asks if she'd invest in a bar he's bought and applies some guilt tactics on Watson. She asks how much he needs. Returning to the Brownstone, Watson is surprised to find a shirtless man examining a projection of the math from Soto's house. Finding Holmes in the kitchen, he explains the man is Harlan Emple, a math professor, who is determining if Soto's equations were worth killing over. Watson asks Holmes for an advance of $5000 to help Joey but they are interrupted by Emple. He explains that Soto was trying to solve P vs. NP, a math problem with numerous applications and has a $1M prize for solving it. Emple indicates that Soto was close to solving the problem. From the handwriting, Watson deduces that Soto had a male partner and Emple indicates that another P vs NP expert, Tanya Barrett, may know who the partner is.

S02E02-Watson Emple Holmes
You think a million dollars could be a motive for murder?
A college professor, Holmes and Watson question Barrett in her office. She knew Soto but quit working on P vs NP years before. Watson mentions Soto's partner but Barrett indicates Soto was a loner. To provide possible partners, she offers math journals but Holmes finds a proof in one journal matching the partner's handwriting. Barrett identifies the author as Cyril Nauer. Holmes calls Bell to report the lead but Bell says that they've found another dead body, Cyril Nauer. At the Morgue, Holmes recounts that Nauer was killed an hour after Soto and, by the same killer. Watson notes that CSU found dog hair on Nauer which Holmes identifies as Boston Terrier. Watson reminds Holmes about the salary advance and describes the circumstances leading to Gerald's death and how much she appreciated that Joey didn't blame her. She confesses he's asked her for money before but they are interrupted by a call from Bell summoning them to Nauer's apartment.

S02E02-Watson Holmes morgue
It was a difficult process, as you can well imagine.
On the street outside Nauer's, Bell reports that they found a listening device in his apartment. Holmes deduces that he was being watched as well and sees a camera on a post aimed at Nauer's window. Hailing a cab and jumping on its roof, Holmes finds a signal jumper on the back of the camera which can be traced back to the receiver. The receiver belongs to Roe Encryption whose president, Linus Roe, is questioned in his office by Bell, Holmes and Watson. Roe denies knowing Nauer until he finds out he is dead. Roe tried to fund Nauer's work but when he wouldn't take any money, he turned to surveilling him. He explains that an application that could crack any computer security system could be built from the solve of P vs NP. With the application, Roe's company could built a counter-solution. He says they were also watching Soto. However, Roe brought Soto and Nauer's work to Tanya Barrett to evaluate who told him that they weren't close to a solution, contrary to Emple's evaluation.

S02E02-Roe questioning
The digital world would be your oyster.
In "the box" at the 11th Precinct, Barrett says that although Soto and Nauer had made great progress on P vs NP, they were only a third done and it would be years before they solved it. She lied to Roe hoping he would back off pursuing a solution as she knew what he was doing was wrong. Captain Gregson confirms she owns a Boston terrier and Holmes points out she owns a pistol the same as the murder weapon. She says the pistol was stolen and denies killing Soto and Nauer to use their work. She provides an alibi during the murders, she was having dinner at a restaurant with a man, Wayne Kaneshiro. The restaurant sends security video with a timestamp that confirms Barrett's alibi. At the Brownstone, Holmes does sit-ups while looking at an evidence wall which includes others working on P vs NP. He tells Watson that Kaneshiro confirmed Barrett's alibi and gives Watson the money she asked for. He doesn't like that Watson's guilt is being taken advantage of and gives her more than she asked for so Joey won't bother her again.

S02E02-Barrett in box
I got to the restaurant around 8:30. I didn't leave until after 10:30.
Watson posits that Barrett is working with a partner but Holmes believes she is being framed. The next day, Holmes asks Barrett if she has any enemies. She mentions her ex-boyfriend, Jason Harrison, threatened her after their break-up. Harrison is questioned at the precinct where he denies knowing Soto or Nauer and when he's confronted with threatening emails he wrote about Barrett, Soto and Nauer and, an on-line purchase of pistol ammo, he insists he's not behind any of them. Gregson reports that Benny Charles has regained consciousness. In the hospital, Charles confirms that Barrett shot him and Soto. At the precinct, Holmes and Watson review an evidence wall, stumped. Holmes comments that Watson isn't going to pay Joey to go away and equates the $22,000 he gave her as the value of 5,500 beers. Watson asks how he came up with $2.50 a beer and he mentions that a man in the restaurant security video paid $10 for four beers.

S02E02-Evidence wall
You know we're going in circles here, right?
The video time stamp indicates the man bought the beers at 9:46pm but Watson indicates beers are only that cheap earlier, during happy hour. Holmes says it's a digital time stamp and they come to a realization. Barrett is confronted in a classroom where Holmes says she'd solved P vs NP but needed time for a programmer, Kaneshiro, to write the code to use it to steal from several banks. She killed Soto and Nauer as they were close to the solve, which would have ruined her plans. Claiming they have no proof, Bell indicates that Kaneshiro confirmed the events once they were able to demonstrate that Kaneshiro hacked into Harrison's accounts to write phony emails and had altered the security footage digital time stamp.

I don't know where you're getting this.
Watson meets with Joey, and says she'll help him but will only pay for his education. Joey tries to guilt her into using the money for his bar but she remains firm. Returning to the Brownstone, she finds Holmes looking at the P vs NP projection from Soto's wall one last time. Tanya Barrett and all materials from their case are being taken by the NSA. Holmes congratulates her on the solution for Joey, which demonstrates goodwill but will stop him from using her for money. Watson says she'll pay him back but Holmes doesn't care. To her surprise, Holmes asks to accompany Watson the next time she visits Gerald Castoro's grave.

S02E02-Watson Holmes ending
What do you mean, last look?


  • Erin Doherty - Lightning Rod plays as Watson meets Joey Castoro at the Court Square Diner.


  • The episode was produced as the third episode of the season, but was aired as the second episode.[1]
  • Watson and Joey Castoro have coffee at the Court Square Diner located in Long Island City.
  • The solution to this case is similar to that of Dorothy L. Sayers's classic mystery novel Have His Carcase, in which all the evidence points to the killer having committed the murder, except his alibi seems unshakable. Once the detectives alter the time of the victim's death, the case is solved.


But I've come to learn over the last few years that there is nothing on this planet quite so toxic as guilt.

— Holmes to Watson


Episode Stills[]

Behind the Scenes[]