A disguised gunman executes a taxi driver; the cabby was a former Navy systems technician and petty officer third-class; G is involved as a former alias in an old case; the Callen team investigate; they find the pieces and the bad guy.

While G, Sam, and Kensi visit Keelson's computer center and physical records, the computer files self-destruct, and the premises ignite and burn; however, they rescue several documents, which include a list of G's 37 foster homes and orphanages plus five more addresses, which he does not recognize. The team, tracing clues, find a birth certificate for Amy Callen, now known as Amy Taylor; Hetty sends Sam and Kensi to Amy's place but chats up G; Eric gives G some data; Sam and Kensi find a tossed pad with nobody at home; G pursues a lead and finds a trashed home, the infamous Trent Kort, of the CIA, with whom G previously worked, and who shows him the body of a contact killed by bizarre means. Eric gives clues to G, who traces a lead to Amy, who as a teenager said that she had a brother; while pursuing a van, G runs into trouble, but he finds Amy, who's truly Hannah Lawson, but who tells G about Amy; the cavalry arrives, so they all take care of the bad guys.