The CEO of a biotech firm is killed when his car explodes. NCIS investigates and finds traces of white phosphorous on the engine. Questioning a Vice President and scientist leads the team to discover the victim had just discovered a profitable vaccine. Nell reports a large amount of white phosphorous was stolen by a criminal organization, Omni, and that the victim was a member of a racing club. Kensi and Deeks investigate and Deeks finds white phosphorous in the victim's garage. Eric gets an alert that someone is stealing the samples of the vaccine. Callen and Sam chase down the thief, the scientist, who reveals Omni kidnapped his family in exchange for the vaccine. The team heads to the exchange and discover the Omni boss was a secret investor in the vaccine. Finally, the team is able to catch the killer, the VP, who wanted to be the face of the company. Meanwhile, Deeks returns to the team.