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401Panopticon 409The Devil You Know 417Karma” (Finch)
402Nautilus 410The Cold War” (Greer) 418Skip
403Wingman 411If-Then-Else” (The Machine) 419Search and Destroy
404Brotherhood 412Control-Alt-Delete 420Terra Incognita” (Reese)
405Prophets” (Finch) 413M.I.A. 421Asylum
406Pretenders 414Guilty 422YHWH
407Honor Among Thieves 415Q&A
408Point of Origin 416Blunt

4x11 - If Then Else.png



Air dateJanuary 6, 2015

Running time44:03

Production code3J5411

Written byDenise Thé

Directed byChris Fisher

Viewers10.08 M

ID(s) from IntroID.411/0106.15 (Reese, Fusco, Root)

Images (31)


Chess is just a game. Real people are not pieces. You can't assign more value to some of them than to others.

— Finch, to The Machine

"If-Then-Else" is the 11th episode of season 4 and the 79th produced hour of Person of Interest. It originally aired on January 6, 2015.


Samaritan launches a cyber-attack on the stock exchange, leaving the team with no choice but to embark on a possible suicide mission in a desperate attempt to stop a global economic catastrophe.

Origin of the Title

In computer programming, the keywords if, then, and optionally else make up the most common form of conditional expression. In an if-then(-else) clause, a certain block of code (the then clause, though not all languages use that keyword) is executed if (and only if) a certain condition is met. The structure may also have an else block present which it will execute if the condition fails. The else clause may include its own conditional, which is often simplified as else if. The phrase is a metaphor for the consequences of choices: what happens if we turn right rather than turn left, or separate rather than stay together, choices the Machine must explore.

Main Plot Points

The events in this episode are in Machine point of view.

  • Persons of Interest: The team: Reese, Finch, Fusco, and Root, who find themselves pursued through the bowels of the New York Stock Exchange by Lambert, Martine and a team of Samaritan's assets.
  • As Samaritan crashes the market, Team Machine is going to the stock exchange's servers to install the software to prevent further market collapse.
  • Shaw is on the subway trying to talk Gary out of blowing up New York and getting the codes out of him.
  • When the team discovers that it was a trap, the Machine starts to work on different strategies to prevent financial crisis and evacuate its assets from the server floor, discarding those which lead to deaths of the Team's members. Each possible line of events is shown in the real time; thus, Finch, Reese and Root are found dead in different simulations.
  • In Option 336,742 Finch and Root head to the server room while Fusco and Reese disable the elevator locks. This option is discarded because it leads to Samaritan calling backup, Shaw kills Gary before he can give her the codes, Finch getting killed, and Root, Shaw, Reese, and Fusco getting captured by Samaritan. Secondary Objective is failed. The Machine did not get Samaritan out of the NYSE servers and the stock market crash destroys the economy and triggers another great depression. Primary Objective is also failed. Finch is terminated and The Machine needs Finch to operate and with his death Samaritan takes over the world.
  • In Option 506,738 Root and Finch disable the elevator locks while Reese and Fusco head to the server room. Finch powers up the generator while Root gets the fire ax. This option is discarded because Samaritan still calls backup, Gary tries to blow himself up and Shaw kills him before he can give her the codes, Fusco does not put the password in in time, Fusco gets locked in the closet by Reese, Root and Reese get killed, and Shaw gets captured by Samaritan. Secondary Objective is failed. The Machine did not get Samaritan out of the NYSE servers and the stock market crash destroys the economy and triggers another great depression. Primary Objective is also failed. Root is terminated and The Machine needs her to communicate to the team. Reese is also terminated and The Machine needs him to carry out the mission. With their deaths Samaritan rounds up the rest of Team Machine and still takes over the world.
  • As the result of the best option available 833,333 is selected. Shaw pacifies Gary and gets the codes. Finch, Fusco, Reese and Root successfully install the software and move to the elevator exit; however, the controls are locked and only Shaw's sudden appearance significantly increases their chances of survival when they are stuck in the shooting with Samaritan's operatives. Root flirts with Shaw and makes it clear she's attracted toward her. Shaw reciprocates, but says they would get be a disaster.
  • With the elevator not working, Shaw notices a red override button at the other side of the room which should start it; she kisses Root, forces her into the elevator, and locks the Team in while pressing the button and shooting at Samaritan's operatives. However, Martine shoots Shaw; the rest of the team watches her fall and Martine prepare to fire a final shot, and then the doors of the elevator slam shut.
  • Root cries over Shaw's sacrifice


Multiple flashbacks, in which Finch teaches the Machine to play chess and work on different possible strategies, are shown. The machine starts with a weak opening move, f3 Barnes Opening which can lead to Fool's Mate if played. In the second flashback The Machine plays Queen's Sacrifice which is a risky move. In the final flashback The Machine wins and selects the proper strategy.

Episode Notes

  • This is the first episode in which the Machine explicitly identifies Fusco as an asset. He is identified as a secondary asset in the third simulation, when the probability of his survival is calculated.
  • The drawing in the episode is "Dancer Adjusting Her Slipper" by Edgar Degas (1873). Between 1873 and 1874, Degas made a series of pencil, chalk and graphite studies of ballet dancers, shown in different poses and from different angles. These drawings served as preparatory studies for his ballet themed paintings of the same period.[1]

    Close-up of the drawing

  • The drawing illustrates the consequences of even the smallest choices on a sequence of events, a theoretical construct known as the butterfly effect. A component of chaos theory (which suggests nothing in the natural world is random), the butterfly effect posits that even the smallest action (such as when a butterfly flaps its wings) sets off a series of increasingly larger changes in seemingly unrelated events over a period of time (such as the trajectory of a hurricane).
    • A number of films and television programs have played with the consequences of choices, including the film Groundhog Day, in which a day repeats over and over, allowing one man to reset his priorities, and the Doctor Who episode "Turn Left", which explores that happens in one character's life when she makes a left turn rather than a right turn at an intersection. Such choices have also figured in literature and poetry, notably in the Robert Frost poem, "The Road Not Taken," which begins with the famous line, "Two roads diverged in a yellow wood, And sorry I could not travel both"
  • The command Finch asks Fusco to enter is most likely env x='() { :;}; echo vulnerable' bash -c "echo this is a test", a command used to check if a computer system is vulnerable to shellshock, a software bug which allows a user unauthorized access to a server.
  • To celebrate Person of Interest airing on Netflix starting September 1, 2015, asked Jonathan Nolan and Greg Plageman to pick a few of their favorite episodes. Nolan picked "If-Then-Else" as one of his favorite episodes because it was an amazing idea.[2]

The Last Stand

When Samaritan springs its trap, the team finds itself pinned down in the Stock Exchange break room, where it must either stand and fight, or find a means of escape. Fusco exhorts Reese to "Remember the Alamo!", which suggests he sees their situation as hopeless: their last stand. A last stand is characterized by military troops who must take a defensive position against overwhelming odds, generally fighting to the last man. History has documented numerous last stands, from the Battle of Thermopylae (480 BC) to Custer's Last Stand at the Battle of the Little Bighorn (1876), which are less remembered for who won, than for who fought well, and died.

  • The Alamo

    The Battle of the Alamo (Texas Republic, 1836) gave birth to the cry, "Remember the Alamo!" The battle began when Mexican General Santa Anna laid siege to a small fortification in what is now modern-day San Antonio, Texas. The Alamo was occupied by Texians, Americans attempting to claim Mexican Texas territory for a new Texas Republic. Santa Anna met 100 Texians at the Alamo with 1500 troops, and after thirteen days of fighting, killed most of the defenders, including famous Americans Davy Crockett, James Bowie, and William B. Travis. Santa Anna's victory was short-lived; six weeks later, the Mexican army was defeated at the Battle of San Jacinto, and Texas became independent from Mexico.
  • Shaw's arrival at the end brings in another famous historical event associated with sieges: the arrival of the cavalry. As American and European immigrant settlers began homesteading traditional Indian lands in the American west, they depended upon the cavalry, small units of mounted soldiers, to defend them from attacks by Indians who saw their homeland, food supply and traditions as threatened by these new settlers. In fiction, this event has evolved into a much used trope: the last minute arrival of help designed to rescue imperiled characters, often surprising the viewer, if not the characters.
  • Both Reese and Shaw engage in another trope seen during the last stand: the heroic ultimate sacrifice. In the second simulation, Reese makes himself a target to protect the others, but does not die before he takes out several Samaritan operatives with a grenade. In real time, Shaw appears to sacrifice herself to get to the red emergency release button, allowing the others to escape in the elevator.

Production Notes

  • This is the second episode of the Person of Interest Trilogy arc. The arc concludes with “Control-Alt-Delete”.
  • This episode also concludes a story arc beginning with “Honor Among Thieves” in which Shaw is identified and pursued by Samaritan and its operatives.
  • The last scene of each episode is followed by the POI title card. When there is a new episode the following week, Michael Emerson's voice over is included, inviting the audience to "stay tuned for scenes from our next episode." In this episode, the invitation was on-screen, from Samaritan.
  • The opening scene with Finch and Root was filmed around 11 Broadway, close to the actual New York Stock Exchange.
  • Scenes in the basement of the stock exchange were filmed in an actual government server farm in Staten Island.
  • The super slow motion scenes were filmed with a Weiss camera, which was also used to film the opening credits.
  • Denise Thé was the one to pitch the idea, as "the slow-burn perfect evolution of the Machine being able to predict what we can do".[2]

Bloopers and Continuity Errors

  • The red second hand on the clock is clearly shown in an extreme close-up shot, but the second hand is missing when they begin to move in the first simulation.
  • In the first simulation, when Finch and Root in the hallway to serve room. The surveillance feed "SUB6_HALLF_05" showing the hallway is different from the hallway where shootout took place.
  • In the second simulation, Root gives the briefcase to Fusco, but when they get up, the briefcase is in Finch's hands. When they reach the door, Fusco is holding it again. A moment later, it's in Finch's hands. When they leave the room, Fusco is carrying the briefcase.
  • In the third simulation, the banker urges Shaw to shoot Gary despite the fact that Shaw was never shown to draw her weapon.
  • In the scene after option 833,333 is selected as the best option available, The Machine is about to contact Root. The timestamp of the surveillance feed "SUB6_BRKRM_05" should be showing 15:08:00 instead of 15:18:13.
  • When the team prevents the financial crisis, the surveillance feed's timestamp says 12:12:23/24, instead of somewhere between 15:08 to 15:16.

What Happened to Shaw?

We're not sure, and may not be for some time. The last sound we heard was the door of the elevator closing, or possibly a gunshot (we can't be sure which), and Shaw's status is unknown. Why? Sarah Shahi found out she was pregnant just as the season began filming, and soon after, learned she was expecting twins. Her doctor recommended she stop working by her sixth month, which she has now done. She has left the show for the time being, with the option to return. However, she recognizes the demands that twins will place on her, and is unsure when they will allow her to return to work at the level of commitment she needs to play Shaw for some time, if at all. The producers have written her out with the door open, so she can return in time, should she want to. Read more here, and see what the cast and producers had to say here.

Oh, and about that kiss... what can we assume? Not much. See what the producers and Shahi have to say here. They can't even agree what it might mean. Time will tell.


  • "Fortune Days" - The Glitch Mob (during the shootout scenes in each of the scenarios)


  • Reese, Fusco, and Root have the same intro ID, but Finch has no intro ID.
  • Delia Jones is an unseen secretary during the episode and is later revealed in “M.I.A.


  • "This apparent madness has a method, Mr. Lambert." (Greer) can be compared to "Though this be madness, yet there is method in it." (Polonius in Hamlet)
  • "What's the point of saving the world if you can't enjoy it?" (Finch) and "What good's saving the world, Harry, if we can't enjoy it?" (Root)
  • "There are more possible games of chess than there are atoms in the universe." (Finch, to The Machine)
  • "If you wanna die, okay. But die for something that you love." (Shaw)
  • "There's no time like the present." (Root, to Shaw)
  • "The lesson is that anyone who looks on the world as if it was a game of chess deserves to lose." (Finch, to The Machine)

In the third simulation, the Machine accelerates the action, at which time we hear the characters describe their dialogue rather than actually delivering it:

  • "Coolly delivered sadistic warning." (Reese)
  • "Self-deprecating inquiry into the time necessary to infiltrate system." (Fusco)
  • "Funny yet insightful retort." (Root)
  • "Mildly agitated declaration of mission completion." (Finch)

This sequence demonstrates how well the Machine has come to know each of these characters, who it is able to describe in terms of their response style.