Picking up where episode 418 left off, Callen and the NCIS:LA team work with Paris and the NCIS: RED team to track down suspected terrorist Robert Spears. When intel suggests that he is headed to El Centro, Mexico, Hetty sends the RED team after him to track him down, while the LA team stays to interrogate captured terrorist Ari Yousef Sayed. This leads both teams to a smuggler and arms dealer named Carlos Ramirez, who owns properties in El Centro. The RED team engages in a firefight with Ramirez and his crew, but he escapes. Eric and Nell locate him in Bombay Beach at the Salton Sea, but when the RED team arrives, they find Ramirez dead from a gunshot wound to the back of the head. Hetty begins to suspect that they are dealing with a contract killer, so she has Kensi and Deeks look into all the unsolved murders that involved similar killing methods. Both the LA and RED teams follow the evidence to find the real shooter, Louise Edwards, a contract killer hired to eliminate Spears, Santoso, and Ramirez. Callen engages in a hand-to-hand battle with Spears and emerges victorious, while Roy saves Paris after Edwards gains the upper hand on her in a shootout. After wrapping up the case, the LA team returns home, while the RED team, Roy included, packs their bags for their next mission.
