The BAU leads the investigation into a string of murders taking place in supposedly haunted houses in Lewiston, Maine.
Evidence from the murder of a Navy captain leads the NCIS team to Ducky's deceased mother; the team exchanges holiday gifts; Gibbs has Christmas dinner with Fornell.
The Cyber team tracks a vigilante who is killing the biggest offenders of objectionable posts on social media websites. Jamie-Lynn Sigler guest stars as Sasha Boyd, a social media content moderator.
Flynn leads the others on a rescue mission, which leads them into a subterranean trap filled with ancient Egyptian werewolves.