Kensi and Deeks go undercover as a married couple housesitting in a gated community to identify a Russian sleeper agent believed to live in the neighborhood; a Russian businessman, who's also a link to the unknown agent, dies at a local hotel. G and Sam visit an old Russian friend of G, and Kensi tries to visit an aged neighbor; they all get reactions; Eric finds a lie, so Kensi sniffs around and finds herself in a chick fight; the other girl agrees to tell all, but she too dies; still, though, she gives a Russian name, and she says that he is nearby. G and Sam return...