Sam receives a prerecorded phone call from Frank Turner, a former coworker and ex-CIA agent, asking for his help. The only problem - Frank was murdered in his downtown apartment and the call was designed as a failsafe, which means Frank knew someone was out to get him and that he needs Sam to solve the case. The team finds specific clues that Frank left behind, including an award winning poodle with an attitude and a coded message hidden in the victims stomach, but none of the pieces seem to connect. Kensi and Deeks go to a dog show with the poodle to track down David Pierce, a breeder Turner was investigating when he died. Turner then leads the team to his parents, who turn out to be Soviet sleeper agents from the Cold War era in possession of a nuclear bomb large enough to wipe out Los Angeles. Sam eventually learns that Turner was trying to track down other sleeper agents in the US before an international arms dealer, Isaak Sidorov, could get his hands on the nukes. The encoded message he left for Sam has all of the agents' names, but they're spread out across the country. Now, it's a race to find the agents and locate the remaining nukes before Sidorov does.