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← Season 1 Person of InterestSeason 2 (Flashbacks in parentheses) Season 3 →
201The Contingency” (Finch) 209C.O.D. 217Proteus
202Bad Code” (Root) 210Shadow Box 218All In
203Masquerade 2112πR 219Trojan Horse
204Triggerman 212Prisoner's Dilemma” (Reese) 220In Extremis” (Fusco)
205Bury the Lede 213Dead Reckoning” (Stanton) 221Zero Day” (Finch/Ingram)
206The High Road” (Finch) 214One Percent” (Finch/Ingram) 222God Mode” (Finch/Hersh)
207Critical 215Booked Solid
208Til Death” (Finch) 216Relevance
Trojan Horse

POI 0219 Main4.png



Air dateApril 4, 2013

Running time43:47

Production code2J7219

Written byDan Dietz
Erik Mountain

Directed byJeffrey Hunt


ID(s) from IntroID.219/2461.13

Images (54)

Don't count me out just yet, Harold.

— Elias

"Trojan Horse" is the 19th episode of season 2, and the 43rd produced hour of Person of Interest. It originally aired on April 4, 2013.


When the number of a leading tech executive comes up, Finch infiltrates her corporation to gather intel, but can't determine whether she is working in her company's best interest, or planning to destroy it from the inside. Meanwhile, Carter continues to question Cal Beecher's integrity after he provides incriminating information about a fellow detective.

Origin of the Title

The term Trojan Horse has its origins in Greek mythology, based in the tale that the ancient Greeks hid themselves in a large wooden horse presented as a gift to their enemies, the fortified city of Troy. When the Trojans pulled the massive horse into the city, the Greeks attacked and won the war. The term has come to mean anyone who enters an organization via subterfuge with the intention of doing harm. In computing, a trojan horse is a program designed to trick users into running it, generally the outcome is damage to the user's system.

Main Plot Points

  • Reese is still following Sameen Shaw as she seeks to revenge her partner Michael Cole objecting to the disparaging story of Cole reported in the newspaper.
  • Monica Jacobs is framed by the People's Republic of China through her assistant and loses her job due to investigating the death of company spy Justin Lee.
  • Carl Elias reveals setting up a chess game with Beecher that there is a powerful unseen "ghost" referring to the head of HR.
  • Sameen Shaw tracks Finch at The Library who has disseminated a news story that Cole was a CIA hero so she decides to investigate Root.
  • Reese, Finch and Monica with the help of Bear discover that massive amounts of information are being collected through a Trojan virus in routers distributed by Rylatech.
  • Decima Technologies is revealed to be gathering intelligence on United States entities and sending some of the information to China as a smoke screen to cover their activities.
  • John Greer is revealed to be the force behind Kara Stanton and her virus.
  • The virus developed by Finch and uploaded by Kara Stanton is revealed to have been specifically created to target the Machine.
  • The Machine continues to be negatively affected by Decima's virus.
  • After learning that Bill Szymanski was innocent, Cal Beecher is murdered by HR.
  • Thanks to Fusco, Carter learns that Beecher was innocent too late.
  • Finch surreptitiously offers Monica a job at his company he started with Nathan Ingram, IFT.

Episode Notes

  • There is increased vigilance on the part of the US Congress regarding implementation of new guidelines on  large-scale purchases of  technology equipment made in China, which was the concept underlying this episode. The concern is that "back doors", unobtrusive means of accessing computer systems with little chance of detection, can be installed, or that "sniffer chips" can be implanted in the computer systems of American companies which operate in China, making them vulnerable to compromise.
  • Finch identifies the virus code as originating with Decima Technologies. Decima is the name of one of the three Fates responsible for the metaphorical thread of life (destiny) in Roman mythology. Decima controls the events and interactions in each life by weaving the thread into a tapestry.
  • When Finch discovers Justin Lee's true identity, a Chinese identity card is shown. The identity code is 15 digits, but in reality, it should contain 18. According to the number, Justin was born in Heilongjiang province, most likely in Harbin, a city north to Beijing. That form of identity code is only used in Mainland China, but according to the card, Justin Lee lives in Hong Kong where it is not used. Also, the card uses simplified Chinese characters while in Hong Kong traditional characters are used.

Production Notes

Bloopers and Continuity Errors

  • When Fusco is listening in on Elias and Beecher's conversation, Elias pauses between "He was clean," and "You got played." In Fusco's recording that he plays for Carter, there is no pause.


Embedded Codes

Main article: Trojan Horse/Embedded codes


  • "You think I should have a hobby. Now what would that be? Hanging around your derelict library with you, your poorly socialized guard dog... and Bear here?" (Shaw)
  • "I'll do everything in my power to determine his identity and render him irrelevant." (Greer, about Harold Finch)



Person of Interest 2x19 Promo "Trojan Horse" (HD) ft. Sarah Shahi