'Person Of Interest' Season 4: Ep 20 Spoilers: Did Taraji P. Henson's Carter Leave "Secret Message" For Reese? [WATCH]

CBS will air an all-new episode of Season 4 of Person of Interest. In Episode 20, will Finch (Michael Emerson) and Reese (Jim Caviezel) find a way to defeat Samaritan by a message from beyond the grave, when an old friend from the past returns, guest star Taraji P. Henson (Empire's Cookie Lyon)?

As we previously mentioned, the fourth season started with Team Machine on the run. With new identities, the group had to lay low or else they would be detected by Samaritan's radar. But all things changed during the recent trilogy, which left Shaw (Sarah Shahi) taken prisoner by the mysterious Greer. Samaritan even sent in its avatar to deliver a message to the President of the United States.

In our recent recap, Reese and Finch discovered their latest POI, Khan (Aasif Mandvi) was being targeted by Samaritan. Finch had to patch things up with Root (Amy Acker) because he needed her help. The group discovered Samaritan has been using Khan's technology to check every file where it could find the Machine's location. Team Machine failed to save their POI as Greer had Khan taken hostage and followed Samaritan's orders to shoot him dead.

According to TV Guide, the Hustle & Flow actress will reprise her role as fan favorite NYPD detective Joss Carter. The last time audiences saw Carter, she was gunned down, saving Reese's life, as they brought down the corrupt organization HR.

In the episode, Carter will appear in flashbacks. In the present-day, Reese (Caviezel) has out solo on a perilous and personal journey. He intends to solve a cold homicide case Carter was never able to close.

Check out the exclusive image and script page from TV Guide here:

Watch Emerson's message to POI fans about this upcoming episode:

We mentioned before, CBS has marked the date for POI's season 4 finale on May 5.

Person of Interest continues Tuesdays at 10pm on CBS.

Readers, are you excited to see Taraji P. Henson back on the show?