Sean Ferris was the USS Chimera's Communications Officer who betrayed his country by siding with some Russian operatives to help them find a nuclear warhead. Once everyone had fled the ship, Ferris sabotaged his crewmates's life vests to make sure that they would never be found. He also hit the ship's cook, Cory Mitas before NCIS eventually caught him and promised to bring him to the brig but their plans were scuppered when they realized that the Russian operatives were on their way to the Chimera.