Ducky is taken out of the autopsy room and put undercover in order to help stop the illegal sale of the Navy's weapons system. When the team captures one international arms dealer, the team learns the weapons system is about to be sold to a dealer known as La Grenouille. With Ducky as a decoy, Gibbs is able to set up a meeting La Grenouille. However, right before NCIS makes their move, they learn another agency has plans for La Grenouille as well.