A man dies in a deliberate hit-and-run incident; the victim was a staffer of a candidate for the US Senate; G and company investigate; Kensi goes undercover as the replacement for the vic; the team solve the puzzle and nail the bad person.

Two weeks ago a Marine lieutenant, Edwin, died in Afghanistan; the local civilian coroner has done an autopsy by the request of the widow, Antonia; she also has hired a private investigator, Stuart, to look into the circumstances; last night someone killed Stuart by slitting his throat; Callen and company investigate. G and Sam meet Antonia, who describes her suspicions about a cover-up; Rose, a medical examiner, explains about the harvesting of tissue, but Antonia objects, saying that Edwin was not an organ donor; Edwin's file has disappeared from the coroner's office. Nate shows up at Hetty's request. Rose becomes a person of interest, and Hetty sends Nate to question her; he takes her to the chat room at the boathouse; a picture begins to appear; Hetty and Nate visit a funeral home, as do G, Sam, Kensi, and Deeks, and they grab the head man; the team finish figuring out the whole thing, and they attend a burial with military honors.

During a birthday celebration, 2 sailors and a dancer are poisoned in a bikini bar. When a radical Muslim group appears to take credit for the attack, the team must determine whether there is any truth to the claim.

An aircraft crashes in Burbank, killing all aboard. At first it appears the pilot inexplicably flew straight into the runway, but as the team investigates they find evidence of murder. Nate returns to evaluate Sam and Deeks.

A man dies in an explosion of his car; he's an undercover agent of the US Department of the Treasury, who investigated an ancient Middle Eastern technique for anonymous transfers of funds; the team solve the puzzle and prevent a tragedy.

Callen and Sam continue their undercover mission to take down a white supremacist group that it's believed to have procured nuclear material, while Kensi poses as Callen's tattooed biker girlfriend; the moment Callen and Hetty first met is revealed.