When countless innocent people are killed in a gas attack on a bus, field agent Natalie Colfax offers her help. Can the BAU prevent another attack?
Jane is suspicious of a colonel and thinks that he is hiding something. She starts to investigate a closed case regarding his wife's death.
Doris goes into labour, so Katie heads to the hospital to be with her, leaving the Ottos struggling find a time to be together for Christmas. Meanwhile, Taylor teaches Oliver how to ask out a crush.
When a marine is murdered at an event for the Honor Flight Network, the NCIS team must rely on an irritable Vietnam War veteran to provide details on the victim's whereabouts.
Over the radio, Leanne and Jesse talk a young girl through how to use the supplies onboard a small plane to build a makeshift defibrillator when her mom, the pilot, loses consciousness.