Flashbacks into his past help tell the tale for Dr. Mallard as he and Bishop travel to England in search of answers to find out why an Englishman murdered in the United States would have a list of deceased Navy men on his person.

After Ducky is attacked by a man claiming to have information about his half-brother who died decades ago, the NCIS team searches for the perpetrator, as Ducky recalls the final emotional days he had with his sibling. Also, with the holidays approaching, Bishop and Jake discuss the future of their relationship.

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.

Flashbacks reveal the murder case that first introduced young Gibbs to NCIS and his introduction to young, new-to-America Ducky.