The Enemy Within is the twelfth episode of Season Twelve of NCIS and also the 270th episode of the entire NCIS series.
The NCIS team searches for a home-grown terrorist after a rescue mission in Syria reveals that an American was involved in the capture of a social worker, only to discover that things aren't what they appear to be with the team later racing to stop an attempted assassination while McGee and Bishop become suspicious of DiNozzo's unusual behavior.
It's late night at a small town in Northern Syria and as music plays in the background, a Middle Eastern man throws meat and some green vegetables into a pot with the man wiping his face, the camera pans out to show another Middle Eastern man sitting in the main room, working on a computer.
Suddenly, the door opens and the two greet each other before the new arrival switches off the radio while his companion has abandoned the weapon and is now holding an AK-47.
Upon hearing helicopters, the three split up just as the sound of helicopters is heard overhead.
The new arrival opens the door, only to get instantly killed by gunfire, revealing that the shooter is a United States Marine.
The Marine then sweeps, followed by his colleagues and they take down a second terrorist, shooting him dead.
As the second terrorist hits the ground, dead, the Marines sweep the room and upon entering an area, encounter the third and final terrorist although that terrorist is soon killed.
Once all the terrorists in that area are dead, the Marines sweep through the area.
Another terrorist emerges but the Marines shoot him.
As the group sweeps in, one Navy SEAL gestures towards a door, stating, "Door. Go" while another Navy SEAL says, "Hit it".
As two Marines head up to the door, one applies a charge to the door and both duck in the corner with the charge blowing the door off in mere seconds.
Once the door's free, the two Marines then head into the room, one Marine using the flashlight on his gun while another stands guard.
In the room, the Marine comes across a young woman who identifies herself as an American while the Marine states that he's a SEAL while telling Sarah that they should get her out of here.
It then cuts to Sarah Goode who lowers her hijab, obviously relieved and overwhelmed with joy while helicopters are heard flying in the background.
In the basement as a ZNN reporter states how after a week of recovery and reintegration at the Landstuhl Medical Center in Germany while informing the audience that twenty-eight year old social worker Sarah Gorde is on her way back to the United States, NCIS Special Agent Leroy Jethro Gibbs is busy cutting through a plank of wood with a small end eventually falling to the floor.
The ZNN reporter remarks that when asked, a State Department spokesperson would not disclose Goode's destination and the report shows Goode being escorted out of the hospital in a wheelchair while Goode herself is seen talking to a doctor.
"Gibbs, mind a visitor?", a voice calls.
Gibbs then stops measuring, instead choosing to dump the plank onto the ground just as NCIS Director Leon Vance arrives in while in the background, the ZNN reporter remarks that it's a happy ending to a year long ordeal.
Vance then places a box on the table with the two exchanging greetings.
As he removes his coat, Vance remarks that they're bringing Goode to Washington and putting her up in a hotel before he throws his coat aside while also revealing that Henderson at the State Department requested NCIS's help debriefing Goode.
Vance also states that he'd like Gibbs to handle it.
|Leroy Jethro Gibbs||Mark Harmon||Special Agent in charge of the NCIS Major Case Response Team.|
|Anthony DiNozzo||Michael Weatherly||Senior Special Agent and second-in-command of the NCIS Major Case Response Team.|
|Timothy McGee||Sean Murray (actor)||Special Agent of the NCIS Major Case Response Team.|
|Abigail Sciuto||Pauley Perrette||Chief Forensic Specialist for the NCIS Major Case Response Team.|
|James Palmer||Brian Dietzen||Assistant Medical Examiner for the NCIS Major Case Response Team.|
|Eleanor Bishop||Emily Wickersham||NCIS Probationary Agent.|
|Leon Vance||Rocky Carroll||Director of NCIS.|
|Donald Mallard||David McCallum||Chief Medical Examiner for the NCIS Major Case Response Team.|
|Tobias Fornell||Joe Spano||FBI agent and Diane Sterling's ex-husband.|
|Zoe Keates||Marisol Nichols||DiNozzo's former colleague and new girlfriend.|
|Chris Hegarty||Sterling Macer Jr.||Assistant Director for Homeland. Previously appeared in the Season 2 episode, Forced Entry (episode) which aired eleven years ago. At the time that episode aired, Hegarty was a Marine assisting NCIS in regards to a case concerning a Marine wife.|
|Sarah Goode||Lindsey Kraft||A hostage later revealed to be a terrorist.|
|Rachel Nasry||Stephanie Erb||A woman who appears in the episode.|
|Kyle Nasry||Kevin Joy||Rachel's son.|
|Chelsea||Rachel DiPillo||A woman who appears in the episode.|
|Cabbie||Darryl Alan Reed||A man who appears in the episode.|
|Newscaster (The Enemy Within)||Paul Magers||A man who appears in the episode.|
|Randall White||Arlen Escarpeta||Former Army Specialist. Later commits suicide by shooting himself in the head with a handmade gun after being confronted by NCIS.|
|Musa Ibn Hasan||Zadran Wali||Imam.|
|SEAL Team Leader||A.J. Castro||A man who appears in the episode.|