Navy Lt. Dominic Pine is killed at the DLA (Defense Logistics Agency). He was the aide to Vice Admiral Janet Kleibor.
Bishop finds a gift pen beneath the body.
Tony arrives home to find his father waiting for him, having been let in by the building manager. Tony Senior tells Tony that his fiancé left him and that the wedding is off.
McGee notes that whoever was driving the car had a radio-frequency key card that was re-programmed to override the DLA's gate system. Bishop notes that the card had an embedded Trojan Horse that disabled the security cameras.
On Gibb's advice, Tony distracts his father from his depression by getting him to do an activity. In this case, he got him to re-caulk his tub.
McGee and Bishop interview Pine's girlfriend Gloria Hernandez.
Admiral Kleibor tells Gibbs and Tony that she had sent Pine to her office to pick up the gift pen that was supposed to be given to a friend on the commissioning of The Madison. She says she blames herself for his death.
Abby creates a set of pyjama bottoms for Tony Senior, with death heads printed on them.
Abby discovers that the reason for Pine's death was that someone wanted to steal a painting called "The Chesapeake". They left a fake copy of the painting behind.
Tony Senior shows up at the bullpen and offers to give them a tutorial on the underground art world.
Tony Senior suggests that they pose as underground art aficionados and put in an offer on the stolen painting in order to lure the thief to them.
Tony Senior and McGee visits an art forger named Harry Swann to get information on the fake painting. When Swann notices that the painting is in an evidence bag, McGee pretends to be an outraged boyfriend who wants to hurt the man who stole his model girlfriend. He tells Swann that the man painted the fake picture.
Swann promises to hunt down the forger's name and call McGee.
After the getaway car is found, Bishop finds the empty frame for the painting, plus the flashlight that was used to murder Pine.
Abby finds blood spatter on the empty painting frame, belonging to Brian Khosa who was working undercover in Pakistan when he was killed last year. She surmises that the missing painting was present for two murders - that of Khosa as well as Pine.
Gibbs and Bishop meet Khosa's CIA boss Officer Dale Harris who tells that Khosa was working hard to convince a terrorist group called Al Zalim of his loyalty when he was killed. He was supposed to assist in planting a device at the American Embassy in Pakistan, but got caught warning them about it. Sameer Aziz and his men killed him.
Abby discovers that the terrorist mission was accomplished, and that they had planted an undetectable voice-activated recording device. She tells Gibbs that the bug was planted in the painting.
Tony and McGee pay a return visit to Harry Swann to find out why he hasn't forwarded the art forger's name to McGee. After revealing themselves as federal agents, Swann confesses that the forger is Gloria Hernandez, Pine's girlfriend. Swann tells them that they forwarded Tony Senior's phone number to her.
Tony and McGee rush back to Tony's apartment only to find Senior missing and evidence that Hernandez had been there.
Abby determines that Hernandez is also Pine's murderer.
Senior calls Tony to tell him that he's at a restaurant called The Adams House, and that Gloria Hernandez has a gun.
Gibbs shows up, pretending to be Senior's accountant. Tony takes a spot at the bar.
Aziz shows up at Hernandez' table and points a gun under the table at Gibbs. After some discussion, Gibbs distracts Aziz and everyone rushes the table to arrest him and Hernandez.
Abby locates the recording device under the painting. She hands it over to CIA Officer Harris who tells Palmer and her that they're heroes.