NCIS looks into the case of Lt. Hill who fell from a bridge to his death. Given his security clearance, they need to determine why and how he died.
They track down a kid who saw Hill fall and find video of the death. Eric tracks down the vehicle through the sound of the car's engine.
The team goes to the suspect's house and they are attacked. A grenade is thrown at the agents and Sam throws it back into the house killing those inside.
A woman was found dead and they track down her husband. He was blackmailed into building a submarine for the drug cartel.
Sam and Callen find the sub, but get caught inside. The sub had been turned into a torpedo and the owners set out to sea with Sam and Callen trapped inside.
Hetty goes to Washington DC to answer questions about the White Ghost and what happened in Afghanistan.