Na golfovém hřišti vojenského námořnického klubu zahyne při explozi před zraky svého dospívajícího syna Joshe plukovník Cooper. NCIS prochází záznamy z klubu, ale nic podezřelého nenajde.

Případ posouvá dál až informace CIA o podezřelé teroristické buòce, takže pátrání vede do skladiště, na které CIA dostala tip od svého informátora. Je to však past, ale Zivě se na poslední chvíli podaří zlikvidovat nastraženou výbušninu, aniž by zničila možné důkazy.

CIA odmítá prozradit svého informátora, nicméně díky McGeeovi se NCIS dostává k tajným vládním dokumentům a získává jméno Mamouna Sharifa pocházejícího z Bejrútu a spolupracujícího s Interpolem. Sharif zprvu nechce mluvit, po slíbené odměně nakonec jisté informace poskytne...

A Marine Colonel Frederick Cooper is playing golf with his son, Josh Cooper at the Army-Navy Golf Club the day before deploying to Iraq. The Colonel has a lay in a bunker; he tries to blast out of this with a sand wedge and instead is blasted by a booby-trapped explosive device. The subsequent investigation brings together Special Agent Leroy Jethro Gibbs’ NCIS team with Army Lt. Col. Hollis Mann’s Army Criminal Investigative Division (CID), the latter having beaten Gibbs to the scene.

Jurisdiction at the scene is complex as the murder occurred at the Army-Navy Club, giving both CID and NCIS authority and a sturdy turf battle. Gibbs and Mann’s introductions are cool, reflecting Gibbs’ suspicious state of mind and old school attitude. However, the observer’s eyebrows should twitch. Mossad Agent Ziva David observed, “Gibbs just found his fourth ex-wife.”

Tony questions the dead colonel's son for details. They discuss things-not-to-say-to-a-grieving-person, and duty.

In another budding relationship, Mann pays Gibbs an unannounced visit at his house, much to his annoyance. Gibbs is finishing his boat by naming her “Kelly” after his dead daughter. Hollis makes conversation, ostensibly because she and Gibbs lead a joint investigation. Plowing too close to the cotton regarding the name Kelly, Mann is treated to the famous Gibbs silent stare. Mann gives Gibbs part of his CID profile "Pressured and impatient, but passionate and loyal." She states that she needed the profile to know before she became involved. "Involved?"says Gibbs, "With the case!" states Mann. Among all of this intrigue, Gibbs and Hollis spend ample time inspecting one another’s anatomy. Later, NCIS Director Jenny Shepard questions Gibbs about his working relationship with Mann, foreshadowing a complex relationship triangle. Indeed, Jenny's initial question 'What's she like?' delivered as if in a jealous tone, is a priceless moment.

The viewers finally see Special Agent Tony DiNozzo’s girlfriend, medical student Jeanne Benoit. Benoit questions Tony on how he stayed single for so long. Tony claims commitment issues and Benoit is not buying, reasoning that Tony has not looked at one other woman in spite of the fact that ample comely ones have walked by. Coyly he answers, “I am patiently waiting to find the right girl.” Benoit further probes if he will ever find her. “I am getting more and more confident by the day” is DiNozzo’s provocative response.

McGee goes to Abby's lab to talk about the pieces of explosive that were removed from the Colonel's body. McGee is rubbing against the lab table in an odd way and Abby decides not to wonder why. And goes on to expound on the pieces of the explosive device, stating that Gibbs wasn't going to like the fact that the detonator was plastic and "off the shelf." As McGee has continued to use the table to scratch, Abby's curiosity is finally needing to know what is wrong. Poison ivy. Abby states he needs a simple mix of carbonic acid and water (?). McGee replies that he is not putting acid there. Abby interrupts him to say that it is a paste of baking soda and white vinegar and gives McGee permission to go ahead and apply it. McGee is noticeably relieved and doesn't care how mad Gibbs will be at the news of the land mine.

While all efforts to accumulate essential evidence continue to fail, Director Shepard reveals to Gibbs CIA intelligence pointing to a suspected home-grown terror cell revealed by a CIA informant. Gibbs is dispatched to a warehouse where he meets Mann and Tony discovers that the true target of a discovered bomb were the two investigative units. Gibbs and Mann clear the building for the bomb squad, but Ziva reenters, with Tony tagging along, disobeying Gibbs, climbing up to disarm the bomb in order to protect evidence. During the humid tension of the bomb deactivation Tony and Ziva have the most deliciously flirting, tempting, titillating dialogue exchange of all four seasons of the show. Tony is definitely conflicted regarding David and Benoit.

Gibbs, grateful for the evidence saved by Ziva’s bomb deactivation, nevertheless expresses his displeasure at her disobedience, threatening should she ever do such again he will “kick [her] ass back to Israel.” Mann enters informing Gibbs that the CIA refuses CID and NCIS demands to speak with their source directly. Gibbs dispatches Agent Tim McGee to hack into the Homeland Security computer system for the name.

McGee identifies the informant as Mamoud Sharif and Gibbs and Mann pay him a visit where he reveals under great distress at their presence how he came to the knowledge of the booby-trapped warehouse. He says he hears things from a variety of places frequented by Moslims, Gibbs presses him, and the informant gives him a VHS tape depicting men discussing the assassination at the golf course as “the beginning.”

Tony goes to visit the son who has decided to enter the Marines right away instead of going back to Princeton. Tony talks about the difference between justice and revenge. "An eye for an eye, a tooth for a tooth!" shouts Josh. Tony observes when you do that "Leaves you with a bunch of toothless blind people" and goes on to state that Josh should do what his father would have wanted him to do.

When Mann and Gibbs enter the squad room from the elevator and Tony says to Ziva "Did you see that?" "See what?" "He let her go first. He never lets anyone go first!" Ziva notes to the group there is an uptick in chatter has been recently detected by Interpol. On the plasma screen it is revealed that the CIA informant’s store has been bombed, killing the informant. Ducky tells that the informant was burned alive before he was dismembered by a bomb. Gibbs and Mann recognize that the terrorist wanted to destroy something they did not want the authorities to find – the videotape. Abby inspects the video tape, which has no sound, by lipreading, then Abby and Gibbs have a brief conversation in American sign language which Col. Mann somehow recognizes as being about her. (Gibbs and Abby are both fluent in ASL.) Abby, watching the people entering and exiting the store. Abby identifies one suspect named Abraham Moussalah who she claims does not mention the golf course incident but does use the rhetoric of “the day of judgement is approaching.” The team try to fill in the details and find the suspect is off the identification grid.

The cell phone that was recovered from the warehouse bomb revealed a telephone number that leads the teams to where the terror cell is on the Georgetown promenade with a similar phone that just powered up. The team finds Abraham, looking at the cell phone, not knowing that he is carrying a bomb in a knapsack chained to his wrist and expecting to be contacted at 3 pm. Gibbs determines the detonator is not the cell phone and suspects a time bomb in the knap sack. Gibbs strikes up a conversation with Abraham. He immediately discovers (or maybe he could tell from looking at him on the bench) that Abraham is an honest, slow-witted innocent, who has no idea what he has been caaught up in. In questioning Abraham, Gibbs discovers that the bag was given to Abraham by the CIA informant Mamoun Sharif and calls for Ziva to deactivate it. Ziva asks if it ok to do that as Gibbs had ..Gibbs then tells her to get at it, but tells the rest of the team to clear out. They all hunker down and watch Ziva do her work as the timer ticks down. In the end Gibbs scans the crowd and believes that Sharif is still in the area watching. In the closing shot, Mann responds, “No, not anymore.”