U.S. Air Marshall Mike Beers is getting ready to leave his hotel room to catch a flight, when there's a knock at his door. Thinking it's his cab driver, he opens it only to be shot dead by a man named Normal Dobbs. Dobbs has killed him because they look alike, and he wants to impersonate him.
Dobbs heads to the airport with Beers' credentials and gun in hand. He bumps into Bishop. Bishop thinks she recognizes him but can't recall where.
Tony meets Bishop and her husband Jake Malloy at the airport. They're on their way to Turks and Caicos, while Tony is there to meet his father.
Back at NCIS, McGee gets a notification about terrorist chatter associated with local airports.
Still thinking about the man she bumped into, Bishop notices something weird about his pant leg. She brings it to Tony's attention, wondering if he's hiding a gun.
Tony and Bishop confront Dobbs, but Dobbs identifies himself as Mike Beers - and then chastises them for blowing his cover as an Air Marshall.
Tony makes a joke to Beers about his name, but Beers doesn't laugh or make a comment. He finds this suspicious, as the real Beers has probably been teased all of his life. So he asks Abby to do a check on Beers.
Bishop takes a picture of the imposter and sends it to Abby, who compares it to the actual I.D. of Mike Beers. She notices that the two pictures do not match, and lets everyone know.
Tony, Bishop and an airport police lieutenant decide to confront the imposter in the men's room, only to burst in and find him dead of a stab wound. His gun is missing.
McGee tells Tony the chatter has changed, and they now suspect that an assassin is at their airport, there to kill one of the incoming passengers.
The NCIS team at the office work together to identify the assassin's target: a man named Hector Gomez, who is being escorted from London to Bogota, because he is wanted for the murder of a rival cartel leader.
The team also discovers who the assassin is - a white-haired man named Alberto Velez. They send a picture of him to Tony and Bishop.
The flight from London disembarks. Tony notices Velez watching the passengers closely.
When Velez sees Gomez being escorted off of the plane, he pulls his gun out. Tony draws his gun faster and guns down Velez.