When the NCIS team captures Goliath, an international arms dealer, they discover that the Navy's top secret "ARES" weapons system is about to go on sale to the highest bidder. Concerned that it might get in to the hands of Iran or North Korea, the team springs in to action to bring down both the seller and the bidders. But when it's discovered that another high priority arms dealer, La Grenouille, is involved in the deal, Director Shepard is adamant that they catch him in the act of purchasing the weapons system, as she had spent months tracking his movements. But when the seller dies of a heart attack, the team is forced to improvise, sending Ducky in as the seller. He is able to make the deal, only to have his cover blown at the last second by another party interested in the case: the CIA. The CIA need La Grenouille for a high priority, top secret mission, and force NCIS to let him go, infuriating the Director, who seems to have a personal score to settle with the arms dealer.