Two men die in LA; a visitor, introduced as an Interpol agent, seeks help with a link to a closed NCIS case; Callen and company pursue a chameleon, who promises to kill G soon and tells why; Granger says he's there to catch a killer.

A driver causes a wreck and shoots to death the second driver; a third one blows away the first; SA Renko of the NCIS is an undercover worker of the gun shop where the first two men worked; the team find the bad guy behind it. [Continued.]

The Chameleon says that he'll walk; he tells about Renko and the Mayfield family; he demands an exchange of himself for an abducted NSA analyst; Granger cuts him loose, and the team escort him to the swap, but G takes action. [Continued.]

The LAPD releases G after an overnight stay in jail; Sam meets him; the two exchange words; G leaves in a taxicab with a tail. At the boatshed Kensi and Deeks talk with Atley, who describes certain matters, including an insurance policy nearby; while Sam watches, an Iranian briefly chats up G, who soon walks away; another Iranian approaches Hetty, but she brushes him off; later G sees the two Iranians together, and he makes a deal with them; the CIA demands an immediate arrest of G; Granger asks Nell for a warrant for both murder and treason; Deeks picks up an item from a bank, company pursues, and fireworks ensue; Deeks drops a briefcase, and an Iranian picks it up; Eric snoops and produces; the Iranians beat and question G; Sam, Kensi, and Deeks make a road trip and take a passenger; the team make another swap; Sam hands G's badge and piece back to him; Hetty returns to her office, and Granger returns her resignation; the two of them chat about their "audacious plan".

A nuclear bomb explodes in a desert in Mexico; G and company investigate; Sam and Michelle go underground; G and Kensi go to Iran and bring back the Chameleon, who takes part in a complex deal to gain the two missing bombs. [Continued.]

G, Kensi, and the office crew continue to pursue the wrongdoers and the missing nuclear bombs while Sam and Deeks remain in custody; later the team gather on a helipad, where they hold a shootout; a NEST team seizes the bombs.