Desean K. Terry

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.

The team heads outside the hospital to help provide medical attention at the scene of an emergency.

When Darwyn discovers that the explosion is a decoy, he leaves a clue he hopes will lead the FBI to the true target.

Sam, Callen, Deeks and Kensi spend Christmas on an aircraft carrier investigating an NCIS special agent's death; Eric and Nell celebrate the holidays at headquarters; Hetty goes on a trip.

As July Fourth dawns, the cell prepares to launch two coordinated dirty bomb attacks on the city of Los Angeles, while Darwyn and the FBI move to shut them down.