After the NCIS team tracks evidence from the murder of a Navy captain to Ducky's deceased mother, Ducky looks back and questions a pivotal life choice he made 37 years ago. Also, the team exchanges holiday gifts, and Gibbs spends Christmas dinner with Fornell.

After Gibbs spots the brother of an "NCIS Most Wanted" suspect, he immediately assumes his former alias and goes undercover with their infamous anti-government militia. Also, Bishop and Reeves partner on an off-the-books investigation.