The murder of a diplomat ties back to the first case Callen and Sam worked on together. While Deeks and Nate track down the actual murderer, Callen and Sam go to Mexico where they meet with Tuhon, a retired assassin and friend of Hetty's. Deeks and Nate learn that the crime was planned by a rival mercenary to frame Tuhon in retaliation for a botched coup years prior. With Callen, Sam, and Tuhon on the run, Hetty leads them to a safe house, where a trap is laid to catch the mercenaries and save Tuhon. Meanwhile, Kensi confronts Sabatino, but both he and Granger deny that he could be the White Ghost.