The episode begins with the team going over Director Vance's abandoned car. His phone is in the car, and they are nowhere close to his house. His security man Wallace says Vance insisted on driving himself home as he seemed fine. Meanwhile, Leon wakes up in an open casket in a tomb, lying next to a desiccated corpse with a note pinned to it: "Your king is vulnerable." Gibbs checks in with Sec-Nav. McGee checks all street cameras. Meanwhile, Sam Ryan drops by. "Are you just visiting or do you already know something I don't?" Gibbs asks. She's just there to offer her help. Vance calls Gibbs. They go pick him up. He remembers leaving the Navy yard and being flagged down by three people claiming car trouble.
He was injected with something. The land belongs to the Whitting family; the body belonged to a man who died on the same ship as Dearing's son 10 years ago. There was a giant jawbone from the equine family in the tomb. Sam recognizes it as Biblical. Sampson in Judges 15. "And he finds a new jawbone of an ass, put forth his hand; slew a thousand men." Meanwhile, Duckie and Palmer go over the well-preserved remains of Whitting. He and Evan died in a terrorist attack against a weak section of the hull. Whitting was on the same deck where the bomb hit. Duckie suggests if Whitting was the first to suffer, Dearing might be pointing at who will suffer next: NCIS. Upstairs, Tony wonders about the chances of them making it to Palmer's wedding. Gibbs wants an old case file from 12 years ago involving a prank. Meanwhile, Gibbs drops by Sam's office and finds her son Parker there alone. Parker immediately grills him on how much Gibbs likes his mom, on a scale of 1 to 10.
Parker knows about Gibbs' wood working. Sam comes in. Gibbs wants more on Evan Dearing, Harper's son. He wants to try to exploit Harper's weaknesses. In the lab, Abby is overcome by the idea that they might all Miss Palmer's wedding. She got DNA from the horse jawbone and narrowed it to two thoroughbred breeds. Meanwhile, McGee and Tony pour through old case files for the prank. It involved a "steamy liaison" between a male and female officer, someone taped it and played it for the whole crew. The guy who filmed it was discharged, but the others were reassigned. One was Evan Dearing. Meanwhile, Harper pulled strings to have his record expunged. After the prank, Evan was reassigned to the ship where he was killed. They think Dearing is targeting NCIS now in retaliation. The case agent, Larson, is retired now and lives on a horse farm. Meanwhile, Gibbs and the team reach the farm and Gibbs notices the horses are spooked.
There are groceries in the truck and the engine is warm. Gibbs calls out to Larson. His house explodes. Later, with crews on the site, Larson's body is taken from the smouldering house. They find a video camera nearby. It filmed them arriving and looking around and then Harper Dearing turned it on himself and says that some people need to learn from their mistakes. He claims that by pointing out the wiring flaws and "sacrificing" a few he has saved thousands of lives. But now that he's done that, it's about payback for his son. Meanwhile, Gibbs watches the tape with Vance. The Navy is on red alert. Gibbs plans to talk to Dearing's ex-wife. Vance is burning from Dearing grabbing him. Gibbs urges him to hit back hard. Downstairs, they learn that after Evan died Victoria Dearing sought counselling and Harper started drinking and became violent.
They divorced two years later. Meanwhile, Abby politely interrupts and asks for everyone if there's any chance they'll make it for Jimmy's wedding. Gibbs' silence is their answer. Down in the morgue, Jimmy asks Duckie if he should cancel the wedding. Duckie essentially tells him that would be letting the terrorists win. Duckie promises to be there. Meanwhile, Gibbs talks to Victoria Dearing. She remembers Harper was angry at the Navy and thinks he believes someone has to pay for taking away their son. Gibbs visits Sam again. She shows him her super fancy computer, programmed for getting in people's heads. She's working up Dearing, including finding people he might trust or distrust. One suggested ally is Jonathan Cole from the Phantom Eight. He must have sold Dearing the microchip. She knows Dearing tried to hire Cole at one point, she suggests setting Cole up to get freed from prison and work for Dearing now.
Dearing calls Sam. He knows about her ex-husband "where he is and how he got there." We see he's outside a boy's prep school as he starts talking to her about her son Parker. Later, cops surround Parker's school. Dearing didn't go near him and that concerns Sam; he's finding their vulnerabilities. At the office, Palmer worked through the night with Duckie and they're getting on a plane in two hours. Ziva got him fine Israeli cotton sheets, McGee got him a long range video camera for when he's stuck at work and Tony gives him a re-gifted DVD. Cole is brought in. Gibbs and Sam sit with him in interrogation as he enjoys freedom potato chips. They show him photos of the wiring fires and point out he made Dearing's acts possible by selling him the microchip. He claims to know things about Dearing, but Sam can tell he's lying. They tell him they want him to go work for Dearing. He jumps at the chance to be free for awhile, saying the fact he could die isn't the catch, it's the fun.
They arrange to make it look like Cole escaped. Tony also told Victoria about him, thinking she knows more than she's saying and might contact Harper. Meanwhile, Abby reports that the accelerant at Larson's house doesn't match any of the other fires. Gibbs gets an urgent text from Sam and goes to her office. Her ex was released from prison today on a bogus technicality. She says he was in prison for a good reason, "he hurts people." She's afraid he'll come after her. She thinks Dearing bought the judge and played her. She fights back tears as she tells Gibbs she's taking her son and leaving. He tells her leaving isn't the answer, but she goes. At night in the office, Tony and Ziva try to convince themselves they're not sorry to Miss Palmer's wedding. Tony doesn't know what he'd do if he had to face all the trappings of a wedding. "Elope?" Ziva asks. Dearing just emailed Cole. "Where Golden Eagle's rest tomorrow at 8 a.m." Golden Eagles are retired Navy pilots; they're talking about a coffee shop where they go.
Meanwhile, Jimmy drops by Breena's room on the morning of their wedding. He tells her he feels like he should be back at NCIS helping them. He suggests they get married now and then he'll go back and after they'll have a big party and go on a honeymoon. She agrees. NCIS stakes out the coffee shop. Cole sits down for coffee and the waitress gives him something from a messenger. It's a cell phone. It rings. Meanwhile, Dearing tells Cole to tell Gibbs that he was never really interested in Director Vance. He was interested in justice. Back in the office, they try to figure out Dearing's next move. They figure he drove Sam away so she couldn't guess. Vance is on his way to meet with Sec-Nav. They replay the background audio from Dearing's call to Cole and hear bells from the Navy chapel and other noises outside their own building. He's nearby.
Meanwhile, Gibbs recaps what was found in Vance's car. Nothing. But they didn't strip it down. Dearing was after Vance's car, not Vance. It's parked right outside NCIS. Gibbs calls for evacuation and the bomb squad. Cole reminds him he worked bomb disposal. Gibbs takes a minute to decide if he can trust Cole and decides he can. Outside, people run in all directions. Gibbs undoes Cole's cuffs. They open the car. Inside, McGee downloads his computer on a flash drive and Vance barks at him to get out. Meanwhile, Cole and Gibbs tear the car apart. Ziva and Tony clear the building inside. Outside, Gibbs sees a small red wire under the upholstery. They slice it open and find tons of C4. Cole tells Gibbs to get clear. "It's not the danger, it's the fun," Cole tells him.
Gibbs sees Abby inside nearby in her lab and goes inside. Cole doesn't have a chance to get started before the phone rings with the message "For Evan." The car explodes. Meanwhile, Gibbs throws himself over Abby in the lab, McGee is totally exposed upstairs as the windows blast in and Tony and Ziva are thrown to the floor together in the elevator. Walking along the beach alone, Duckie gets a call. "Dear God, how many?" He says he'll be there right away. He starts to have trouble speaking; he falls to his knees, clearly having a heart attack or stroke. He falls, not breathing, in the surf. The episode ends.