Meredith and Lexie's father returns to Seattle Grace with stomach pains and a new girlfriend; Alex butts heads with the new OB; Mark bribes Jackson for information on Lexie.
Special agent Cabe Gallo forms a new team of super geniuses, hiring former child prodigy Walter O'Brien to lead a team of his brilliant friends.
Callen, Sam, Kensi, and Deeks cancel their Christmas plans, climbing onboard an aircraft carrier to investigate the murder of a fellow NCIS Special Agent.
The team heads outside the hospital to help provide medical attention at the scene of an emergency.
Youmud Din, or Judgment Day, has arrived as the cell begins its day of terror on LA.