Concluding this week is the fourth series of the hit drama following a team of special agents who investigate Navy and Marine Corps-related crimes. In this dramatic season finale, Tony and Jeanne are held hostage in a morgue; the team is worried about polygraph tests ordered by Homeland Security; and Shepard has a mysterious visitor.

Shepard returns from her conference in Paris and is relieved to see that NCIS is still standing after a week under her reluctant temporary replacement, Gibbs. However, when she gets home, she is bemused to find a bottle of Scotch and a glass on her desk – odd, considering she prefers bourbon.

Over at NCIS, her agents are also confused: they have just found out that Homeland Security requires each of them to undergo a polygraph test. McGee is especially worried, as he has a tendency to panic at the prospect of any kind of test, so Abby coaches him with a home-made version of the polygraph. When Gibbs finds out about the tests, he does some research and learns that the CIA has ordered them to find out why Shepard ditched her security detail and went ‘dark’ for 21 hours during her trip to Paris.

Gibbs heads over to Shepard’s house and confronts her about the hours in question – a security breach which has now put his team in a difficult position. She refuses to divulge where she was, but does tell Gibbs that an “unannounced visitor” has been in her house while she was away.

Tony, meanwhile, visits his girlfriend, Jeanne, at the hospital where she works as a doctor. On the way up to Jeanne’s floor, he shares the lift with sweating, wild-eyed drug addict Bernie and her equally agitated pimp, Nick. They have come to see Devon, Bernie’s brother, who broke his leg when he was hit by a taxi at the airport. Nick and Bernie are desperate to get Devon released, but the doctors are concerned about the patient – he needs surgery on his leg, and is also displaying strange symptoms including an unusually high heart-rate.

When Devon’s condition suddenly deteriorates, Jeanne rushes to his side but is unable to save him. She is horrified to discover that he was a drugs mule who had swallowed a package of heroin, which had burst and killed him. “I don’t like losing patients,” she tells Bernie angrily. “If your brother had told us he was body-packing drugs, we might have saved him.” Nick is more concerned about retrieving the body, but Jeanne tells him that an autopsy has to be done. When a morgue attendant later alerts Jeanne to the fact that Nick and Bernie are trying to get in, Jeanne rushes to the morgue with Tony in hot pursuit.

Tony tries to stop Jeanne from following the deranged pair into the morgue, but she will not be
dissuaded from entering. “I will not let him butcher her brother in front of her,” she insists. Unfortunately, Tony is not armed – but the crazed Nick is, and will stop at nothing to force Jeanne to ‘operate’ on Devon’s body and retrieve the drugs for him. Are Tony and Jeanne going to come out of this nightmare alive?

Meanwhile, Shepard asks Abby to help her identify the mysterious caller who left the Scotch in her study. Abby obligingly runs the prints on the bottle and glass through the database, but the result is not what anybody expected...

Elsewhere, Gibbs recruits McGee to hack into CIA records in an attempt to find out more about the proposed polygraphs. What is the connection between the tests, a secret operation by the name of ‘Lodestar’, the notorious arms dealer ‘La Grenouille’ and the NCIS director herself?