Ep 9. The Devil You Know

The episode "The Devil You Know" is the ninth episode of the fourth season of the television drama series Person of Interest. The episode focuses on a former government agent who has gone rogue, and who has begun hunting down members of his former team. The character is played by guest star John Nolan, who delivers a chilling performance as a man who has lost everything, and who is determined to take out his former colleagues, no matter what the cost.

As the episode begins, we are introduced to the character of John Greer, who is the leader of an organization known as Decima Technologies. Greer is busy working on a plan to take over the world, using a powerful AI system he has developed, but he is interrupted by the arrival of the rogue agent, who has come to confront him.

Meanwhile, the series' main characters, John Reese and Harold Finch, are struggling with a problem of their own. They have been forced to work with a criminal mastermind named Elias, who has information that they need to protect themselves from the authorities. But Elias is proving to be a difficult partner, and Reese and Finch are not sure that they can trust him.

As the episode progresses, the tension builds, as the rogue agent begins to systematically eliminate members of Greer's organization. Reese and Finch realize that they may be next on his list, and they set out to find him before he strikes again. Along the way, they encounter several other characters from past episodes, including Shaw and Root, who are also in danger from the rogue agent.

The action in "The Devil You Know" is non-stop, as Reese and Finch use all their skills to track down the rogue agent and prevent him from taking out any more members of Greer's team. The episode is filled with tense moments, as the characters race against time to save themselves and their friends.

Overall, "The Devil You Know" is a gripping episode that will keep viewers on the edge of their seats. The acting is top-notch, particularly from John Nolan, who delivers a powerful performance as the rogue agent. The writing is also excellent, with plenty of twists and turns to keep the audience guessing. Fans of Person of Interest will not want to miss this thrilling installment in the series.