An unidentified young woman dies in an execution-style shooting while making on survellaince; she had a concealed flash drive containing the encrypted results of surveillance of several people, including G; the LAPD contacts the NCIS headquarters; Director Vance tasks Callen and his team to investigate in cooperation with the LAPD. G identifies the victim as a Russian girl, a short-time neighbor (in Venice, California, near Los Angeles), the last person whom he saw before he took gunfire, six months before (at the end of "Legend II", s6e23 of NCIS). The gang learn about two other deaths and an unhappy coincidence; G talks again with a former friend from Moscow, who provides information; Nate and Hetty have a heartfelt chat; G and Kensi unexpectedly meet another of G's former friends from Moscow; after a game of hide-and-seek G and Sam cuff the bad guy. Nate tells Hetty a bit more about G's personal history; G revisits a familiar place and recalls good memories.
—DocRushing