Liz (Megan Boone) will be all business as she looks for the mole in her team in the upcoming episode of "The Blacklist."

As per the promo, someone is revealed to be working for a dangerous terrorist. Red (James Spader) discovers this shocking fact and will not waste time telling Harold (Harry Lennix) about it. Together, they set out to look for the spy, but the clues appear to be pointing to the three other main members of the FBI task force. One of the three - Samar (Mozhan Marnò), Ressler (Diego Klattenhoff) and Aram (Amir Arison) - is the culprit, but how will the others find out who?

Liz is astounded that one of her friends is committing treason. She is shown expressing her disappointment that the team that is supposed to uphold justice and protect the lives of innocent Americans is going to the dogs. She will make sure to find the mole, but once she figures it out, will she be able to do what is right?

In the teaser, Harold also looks like he knows who the mystery person is. He is shown telling someone that he/she must quickly decide where his/her loyalty lies.

Spoilers claim the spy is Samar. Her sketchy past has always intrigued the fans. Samar has been known to work for the Mossad after the death of her parents. They were killed at the government's orders. Samar is from Iran, but nothing indicates she is connected to any terrorist group.

Meanwhile, IB Times reports that Red's life may be in danger in the next episodes. With Alexander Kirk (Ulrich Thomsen) now out of the picture, speculations report that Mr. Kaplan (Susan Blommaert) will be back to get her revenge. Red shot her in the chest when the full extent of her betrayal was revealed.

"The Blacklist" season 4 returns on Thursday, Jan. 5, 2017 at 10 p.m. EST on NBC.