Booth and Brennan investigate a mall Santa named Kris Kringle who was found dead by two elves. A series of clues makes the murdered mall Santa seem like he's the real deal.
When the paternity of a missing young boy is placed into question, Stabler wonders if he really is the father of Kathy's child. Later, Stabler faces the possibility of losing not only his partner but also Kathy and the baby when she and Benson are in an accident.
While trying to track down a delusional and violent Marine who thinks he's still in Iraq, the NCIS team will learn that the man has been the subject of a secret experiment - and it comes with a high price to pay.
In Montenegro, Bob has a moral dilemma when he disagrees with the team's mission.
Tiffy discovers some information about Molly's past and decides to look into it further.