Navy Petty Officer Collin Barrett is killed by a fall after a struggle in a sports arena. Pride breaks it to LaSalle and Percy that Gregorio will be joining them while they're investigating the Cuidad Natal cartel. They're not happy about it. They all head over to the Super Dome to look into Barrett's death, discovering the rifle that was used to wound Barrett before he fell to his death. A threatening email leads the team to the house of the sender, Hank Clarkson, where his wife Susan reveals that they're trying to save their son. Their son Drew was kidnapped on leave in Mexico and the kidnappers have demanded $1 million ransom. Barrett was negotiating with the kidnappers before he was killed. Gregorio tries to trace a call from the kidnappers to the Clarksons, but the kidnappers catch on and appear to shoot Drew. With acoustics, Patton figures out that Drew wasn't shot. Pride goes to let Gregorio off the hook, telling her the good news. They figure the kidnappers' inside man, Diego Martinez, who has escaped to Mexico. Gregorio tells the others that they have permission to pursue Martinez but not to rescue Drew. They run their plan by Gregorio's boss, Raymond Isler, who approves chasing Martinez, but not rescuing Drew. Susan Clarkson comes to the NCIS office and asks Pride to catch the men who took Drew. He lets her know that Drew is still alive, and that's he'll do everything he can to bring him home. Once they get to Mexico, Pride and Percy go after Drew while the team Gregorio is leading pursues Martinez. While Percy distracts the owner of the nightclub where Drew is being held, Pride wipes out the guards. LaSalle drives a truck to their location, and they escape amid gunfire. Isler asks Gregorio for followup. She feeds him a version that he can sell to State, and the squad skates away cleanly. Pride takes Gregorio to see the reunited Clarksons, so she can understand why his team does what it does.