"The Devil You Know" is the ninth episode of the fourth season of the American television drama series Person of Interest.
The series revolves around a computer program for the federal government known as "The Machine" that is capable of collating all sources of information to predict terrorist acts and to identify people planning them.
A team, consisting of John Reese, Harold Finch and Sameen Shaw follow "irrelevant" crimes: lesser level of priority for the government.
According to Nielsen Media Research, the episode was seen by an estimated 9.04 million household viewers and gained a 1.7/5 ratings share among adults aged 18–49.
Shaw (Sarah Shahi) and Rousseau (Cara Buono) start a gunfight at the department store although neither is wounded.
With her cover blown, Shaw is transported with Root to a safe location where Fusco (Kevin Chapman) picks them up.
Reese (Jim Caviezel) has been assigned to protect Elias (Enrico Colantoni) after realizing he is the next number and noticing members of The Brotherhood are following him.
Dominic and a wounded Link (Jamie Hector) discuss Elias and the people who are protecting him, intending to find who is their financer.
In its original American broadcast, "The Devil You Know" was seen by an estimated 9.04 million household viewers and gained a 1.7/5 ratings share among adults aged 18–49, according to Nielsen Media Research.