An infamous arms dealer, Kurt Renner, is murdered and NCIS: LA goes in search of a black book known to hold the names of weapons dealers they believe the killers were after.
An old enemy turned friend from Hetty's espionage days, Branston Cole, is discovered to be the original holder of the infamous black book.
Hetty, who is protective of Cole, works on her own to try and find Renner's killers knowing Cole's life may be in danger.
Callen becomes concerned with Hetty since he knows she is hiding something from the team and follows her.
Deeks and Kensi go to Renner's house and come upon two men claiming to be NSA Agents.
She kicks their sorry a$$es on a hunch and her instinct was right and the men were French Intelligence, one of many foreign agents descending on L.A to find the book.
Hetty slips away again and meets a man she calls Mattias.
He killed Renner and he tells her what he really wants is Cole, not the book. When Hetty won't divulge his location, Mattias takes her hostage but Calllen and the team were following her all the way.
Hetty knows she has unfinished business with Cole since she was the one who shot him years ago putting him in the nursing home. She returns to his room is shocked to find him shot to death ...