Blikající světla semaforu v morseovkovém intervalu SOS vedou k nálezu mrtvého Johna Maguirea. Muž patřil k námořnictvu a měl na starosti protichemickou a protibiologickou obranu. Zemřel v důsledku přehřátí a nepočítáme-li chybějící oko, nebyly na jeho těle nalezeny žádné jiné stopy násilí. Na místě činu zůstala kamera, s jejíž pomocí kdosi mužovu smrt sledoval.

Stopy vedou k Mamounu Sharifovi, známému z jednoho bombového útoku. Když vyjde najevo, že Maguire dodával vzorky plynu do civilních výzkumných laboratoří, je jasné, že Sharif na něm vzorek otestoval. Otázkou zůstává, co je cílem Sharifova útoku a zda má v plánu látku dál prodat.

The cold opening is of a business man walking down the street, talking on his mobile phone via a headset. He is saying how he wants to "live fast, die young". He then crosses an intersection, on the green walk sign, and is almost run over by a car, which stops. He argues with the driver about who had a green light, and then they realize all lights are green and they are flashing (morse code flashing is used). It is an SOS. Roll credits.

The city traffic workers back-traced the traffic signal to a utility room which has a dead marine who has a missing eye. Room locked from the outside. How did he die? The eye was not the cause of death. They find the room rigged with a CCTV camera. Ducky does an autopsy and tells the history of glass eyes to the deceased. Gibbs and Tony arrive and Ducky says the man died from hyperthermia (elevated body temperature) but the marine didn't suffer any of the conditions that affect body temp control. The major worked on nuclear, biological and chemical warfare control. Ducky found the eyeball that was missing - it was in his stomach.

Abby greets Gibbs when he arrives at her lab. We get the "I'm thinking about getting a tattoo" scene where she asks Gibbs' advice on which tattoo to choose. He is reluctant to advise (he is embarrassed) but she begs. So he asks "where do you want to put the tattoo?" and she realises that he is not, after all, the person to ask. So she tells him about the chemical weapon poison that caused the major's death. Also the camera from the room led to an address for where the person watched via Internet. It was a bowling alley.

Team storms the bowling alley and catches...Mann's team. They tracked the bowling alley for different reasons. They were tracking the bomber Sharif and got to the bowling alley via use of a credit card. Teams find that Sharif's fingerprints (from when he was a CIA informant) are on the crime scene for the major. They decide Sharif was testing the chemical weapon on the major.

Mann remarks to Gibbs it is funny they should run into each other again. Gibbs can think of other words for it...but says it with a goofy smile on his face (McGee watches this interplay, goggle-eyed. Ziva just watches).
They meet Jen who says she flipped a coin with Mann's boss: Gibbs will lead and Mann will join forces with NCIS.

Ziva and Tony go to visit the chemical lab engineer for the source of the chemical (BZ gas). They learn a huge amount is missing (10kg).

McGee in Abby's lab gossiping about the look on Gibbs' face when he saw Mann. Mann and Gibbs walk in on the conversation. Abby puts up Gibbs and Mann's photos and uses the baby image software to generate what their offspring would look like. Abby and McGee then report on their work with the video image of the death. They do geek speak about how they tracked the video down. While they witter, Mann asks Gibbs "How long can they go on like this?" and he mutters "until we stop them", so Mann stops them. They see the effect of the gas on the major: the amount used was 10mg. So 10kg is a million-fold worse.

Gibbs goes home to think while working on his boat. Mann follows. Where's the boat? I moved it. They flirt. She provides takeaway dinner. They debate Sharif's motivation. Gibbs says it's not money: "People get older, realise they want something different" "And you can tell this just by looking someone's eyes? OK, what do you see in my eyes?" "You want me to kiss you" "And will you?" "Yes, as soon as we find Sharif" "That is probably a good idea." "Really, 'cause I was hoping you wouldn't say that."

Sharif phones Gibbs and says he has the BZ Gas. He says he wants Chechen prisoners released. He threatens to release more of the gas...so Gibbs looks on the TV news and 6 people are reported falling sick. Sharif, listening on the other end of the phone, then says "actually, counting you, it's 7".

Ducky checks Gibbs and Mann. Sharif appears to be bluffing. Abby anxiously greets Gibbs when he gets the all clear (and ignores Mann). Ziva and Abby report on what they have been finding out, but Gibbs says that the prisoners are a distraction: that is not what Sharif wants. Ziva, Abby, Mann and Gibbs head into the lift, the doors close. Mann asks what Sharif really wants: Gibbs says "I don't know" "So how do you know it's a distraction?" Gibbs just looks at her. Abby taps Mann on the shoulder, and Mann looks over her shoulder: Abby warns her "Never question the gut". Mann just widens her eyes. Gibbs turns and stares at Abby but she just smiles, very innocently.

McGee finds that 2 victims had red trucks visit them. Gibbs tells Ziva to get Tony to...and Ziva reports he is missing. Gibbs is angry. Find Tony now.

We see that Tony is absent because he is visiting Jeanne, because Jeanne took a rain check on their date. She is irritated that 'men' can't understand 'no'. They make up, plan a bath together. While she is in the bathroom, he spies her E-mail, sees scrolling news on the screen, phones Ziva, hears about the chemical weapon poisoning of 6 people, cancels the group bath.

MTAC: Jenny, Mann and Gibbs discuss that Sharif worked for the pest control company that all victims used. He has taken a truck-mounted sprayer that could be adapted for a small aircraft. Jen tells what she has done to prevent aircraft etc spreading the chemical. Gibbs has a flashback to the Hiatus bombing of the ship in the Med. Gibbs is distracted, and has flashbacks of the ship explosion from 'Hiatus: Part II). Jen asks if is he OK. He says he's fine and then leaves. Jen corners Mann and says that Gibbs is not OK. Jen says she almost lost him 6 months ago and doesn't want a repeat, because they might just lose him if there's a next time. Mann says he can look after himself.

McGee and Abby find that the wire transfer for the money for the chemical involved the engineer at the chemical lab where the BZ gas went missing. They bring him in for interrogation by Mann and Gibbs: they do a double act, successfully. The engineer talks. He framed the major to look like the one who stole the nerve gas. He wanted to scare the public to get the share price of his company up. But the gas is doctored so that it does nothing if airborne. It has to be ingested. He didn't want deaths, just fear to drive the stock market his way.

The team try to work out how Sharif is planning to use the chemical. Sharif phones Gibbs and asks how he feels. They trace the phone call (Sharif invites them to trace his call) but no joy. Gibbs asks who were the ones that died that motivates Sharif to take this revenge. Sharif wont say.

Ducky reports that he has worked out how the major was poisoned: topical application like sunscreen or body oil. Gibbs and Mann depart to Abby's lab immediately whilst Ducky is still talking. Ducky comments that he knows that Gibbs always likes to get his man, but the two seem unusually motivated. Tony just smirks.

Abby reports that Sharif will have difficulties distributing a topical poison.

Team shows that Sharif has been withdrawing money from various banks, in $9k units and that they were all $1 notes. Tony reports that the threshold for withdrawals being notified to the govt was $10k but was lowered to $5k last month. Gibbs is impressed at Tony's up to date knowledge of money laundering regulations. They realize Sharif is putting poison on the cash which the public will handle.

All the while Gibbs has been gradually coming under the influence of the poison which is causing him to hallucinate, and to see things in a haze. One of the ways for the poison to enter the body apart from breathing is through prolonged skin contact - as in the case of Gibbs, where this criminal had impregnated the hand tools he uses on his boat with the stuff, as we later find out.

They spot Sharif is using a WiFi game and they trace him via that. He is online at Union Station. Team pursues him. Gibbs keeps getting woozy and flashbacks (but he is too stubborn to get doctor's help, knowing he could be poisoned?) He spots Sharif, Sharif runs, spreading the poisoned money. Public flock to it, so team has to prevent people touching it, leaving Gibbs alone pursuing Sharif into men's room. But the poison in Gibbs' system kicks in and he collapses. Sharif put poison on the hand tools. It is undetectable until it reaches your bloodstream. Sharif tells how a smart bomb killed his family. So Sharif takes aim to shoot Gibbs but Mann arrives and shoots Sharif first. Team arrives and says national guard is coming, with the antidote. Gibbs is seeing double.

In Mann's bedroom, she is watching TV. She gets a phone call and says "I thought you were still recuperating...I'll buzz you in". Gibbs walks into her room: your door was unlocked. He says he is OK, but DiNozzo is mourning at having to burn $100,000. He says he came by to say thank you and kisses her. She says, before we do this I just need to know one thing (Gibbs looks tense) ...how did you get that **** boat out of your basement? (Gibbs smiles).