Do pitevny NCIS jsou dovezeny těla Jeana Paula Ranieriho a jeho manželky Sophie, kteří se stali oběťmi autonehody. Oba patřili k profesionálním zabijákům, u nichž jsou nalezeny falešné pasy a pozvánka na ples NCIS. Agent Gibbs zahájí akci, kterou pověří agenty DiNozze a Davidovou, aby se vydávali za manžele Ranierovi a společně strávili nějaký čas. DiNozzo a Davidová se ubytují v luxusním hotelu. Vědí, že jsou sledováni a odposloucháváni. Musí působit důvěryhodně, dokonce i po sexuální stránce a dochází mezi nimi k jistému sblížení. DiNozzo je v sedmém nebi. Gibbs s týmem mezitím shromažïuje všechny informace o mrtvých, aby měli Davidová s DiNozzem vodítko jak se chovat.

S Davidovou se zkontaktuje podezřelý muž a dohodne si s nimi setkání v restauraci. Odtud jsou prostřednictvím zabudovaných kamer přenášeny veškeré záběry hostů přímo k Abby do počítače, aby je mohla analyzovat. Podezřelý kontakt je žádá, aby mu odevzdali jistý disk.

NCIS se podaří lokalizovat místo, odkud jsou DiNozzo a Davidová sledováni. K překvapení všech vyjde najevo, že jde o agenty FBI, kteří jsou do případu též zapleteni.

NCIS pak zjistí, že si manžele Ranieriovi najal Ceasan, nájemný vrah, ale není jasné, proč by si právě on najímal další nájemné vrahy. Posléze je však zřejmé, že Ranierovi nebyli najati k zabíjení, nýbrž měli být cílem. Chtěli totiž skončit se svým "řemeslem", neboť čekali potomka. Měli však disk se jmény jejich obětí a klientů, o který jevil mimořádný zájem právě Ceasan. Disk je nakonec nalezen při pitvě ukrytý v oku paní Ranierové. Marcos Ceasan se svými společníky je zatčen.

This episode begins with Ziva and Tony, in a hotel room, dressed to impress, and all alone. We are shocked to see Tony and Ziva head to the bed for some serious ‘under cover’ work.

However, the opening as per the title suggests, is actually an undercover assignment. Tony and Ziva have to pretend to be an assassin husband/wife team, because the real assassins are dead. They died in a car accident, using fake passports when Marine CID found them, and heading for the annual Marine Corp Birthday. (This is how and why NCIS got the case.) The team has no idea what to do, and need Ducky to give some Intel on the assassins' lives. As Gibbs puts it, ‘they’re (Tony & Ziva) working blind’. Back at the hotel, Ziva is massaging Tony, when we see that they are under surveillance. (We later find out this is the FBI.)

Tony and Ziva are contacted by their ‘client’ to meet downstairs – with the NCIS team placing hidden cameras and listening devices in the room and in Tony’s glasses. Downstairs at dinner, Tony is forced to eat left-handed (because the real Jean-Paul (assassin) was a lefty) – As they are eating dinner, photos of each person in the restaurant are sent back to Abby for background checks. Ziva gets a call from the ‘client’ and Abby is able to track the call back to the actual hotel, specifically the lobby. Unfortunately, the ‘client’ escapes.

Back at HQ, Director Shepard wants to send in back-up for Tony and Ziva, but trusts Gibbs, so decides not to. There are many Tony/Ziva shots (of them making ‘love’) and of the FBI watching them. Ziva gets McGee to bring up her ‘spy glasses’, which senses the infrared light watching them. McGee and Gibbs are able to locate the room and bust in, showing the FBI agents.

Back at NCIS, Ducky tries to determine how the Raniers lived their lives. The wife had a broken wrist; the hubby had his appendix removed but nothing really helpful for the case. The only thing ‘interesting’ Ducky found was the tattoos on their marriage fingers – the sign for ‘eternity’.

Gibbs calls T&Z, telling them what they know, and when McGee compliments Ziva’s intellect for getting ‘spy glasses, Abby vents her anger. Abby doesn’t realize Ziva can hear her, because they didn’t hang up!

After Gibbs and McGee crash the FBI’s operation, Fornell enters, and starts yelling at Gibbs for ‘straying into their jurisdiction’ – they both go into Gibbs' conference room aka the elevator, and we see that they are actually really good friends. They decide to work together to please both their bosses and to just get the job done.

At the hotel, Tony and Ziva are called by the ‘client’ to meet in the lobby to go to the destination. With the FBI on their side now, NCIS are able to get more men to cover exits, rooms etc. to make the bust when they come out. However, Tony and Ziva never leave the hotel. In the elevator, the waiter (who is a baddie) jams their listening devices, when the real ‘client’ aka Marcos Siazon shows up. We find out he is also a contract assassin, with Abby asking ‘Why would a killer hire other killers to do a hit for him?’ The viewers realize that Sophie and Jean-Paul Ranier (aka Tony and Ziva) ARE the hits!

The Ranier’s wanted to leave the assassin business, because she was pregnant. They had a disk, which had the names of all their hits and clients. The disk was wanted by Siazon because in the wrong hands (esp the feds) it could be very dangerous. The disk is later found embedded in Sophie’s eye socket by Ducky. At the hotel, FBI and NCIS arrest the ‘baddie waiter’, Marcos Siazon and co, with Tony saying that he wants a divorce from Ziva.

Back at HQ, Tony still has a headache (from the beating he took by Siazon’s guards) and Ziva offers to drive him home. Director Shepard, together with Ducky attends the Marine Corps Birthday Ball. Gibbs does not attend, opting to drink at his desk with the flask that was a gift from his dead wife and daughter. Abby wishes him Happy B-day!