Person of Interest Season 4 on return goes If-Then-Else

Person of Interest Season 4 returns Tuesday, January 6, at 10:00 p.m. on CBS with its 11th episode entitled "If-Then-Else." According to the network's official synopsis. 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. "If-Then-Else" was directed by Chris Fisher from a script written by Denise Thé.

The show's regular cast will be seen back with Jim Caviezel as John Reese, Michael Emerson as Harold Finch, Amy Acker as Root, Sarah Shahi as Sameen Shaw and Kevin Chapman as Lionel Fusco. The episode will also feature recurring cast members John Nolan as Greer, Julian Ovenden as Lambert, and Cara Buono as Martine. Guest stars include Chester Jones III (Monty), Andy English (Harvey), Mark Gessner (Gary), Alexis Suarez (Janitor #2), Brennan Taylor (Investment Banker), Victor Joel Ortiz (Bomb Squad Cop #1), Chris Lapanta (Kenneth), Greg McFadden (Businessman), Charles Techman (Old Man), Tuffy Questell (Guard), Gameela Wright (Single Mom), Toshiko Onizawa (TV Reporter) and Isaiah Seward (Security Guard).

"If-Then-Else" takes off following the events shown in episode 10 - with Shaw leaving their Subway safe house to try and help Root and the others while Samaritan engineers a stock market crash on Wall Street. Also shown in that episode, entitled "The Cold War," The Machine agreed to have a talk with Samaritan. There, Root, acting as The Machine's voice, meets with Samaritan's avatar, a young boy. After a tense exchange between the two AI's, it became clear that The Machine will not back down, while Samaritan made it known that it is set on destroying The Machine. A teaser clip for the upcoming episode released by the studio shows Finch taking a hit and Reese is about to set off a grenade. Showrunner Greg Plageman told TVLine that "If-Then-Else" will reveal "more about The Machine's capabilities than ever before." He also teases that it will be a "massive, cool, time-shifting episode that's going to blow some people's minds" and that "something totally shocking happens."