When a diplomat is killed at a Consulate in LA, NCIS gets involved because the prime suspect is someone from their past. Sam and Callen head to Mexico to find a retired assassin, Tuhon. Meanwhile, Deeks and Nate investigate the murder in LA.
Tuhon claims that he is being set up and that's confirmed when Deeks shoots the assassin and finds fake tattoos. Sam and Deeks bring Tuhon to the United States to a safe house. The location was leaked to Carter, the man behind the assassin. Carter believes he has Tuhon trapped, but it was a set up and they are all taken out.
In Afghanistan, Sabatino takes Kensi out on a mission and confronts her about her investigation into him. He denies that he's the White Ghost and takes off. Kensi returns to the base and tells Granger her suspicions. He doesn't believe Sabatino is guilty.