First Look: Ducky's Secret Revealed On NCIS

Jessica Walter as Judith McKnight and Mark Harmon as Leroy Jethro Gibbs

Jessica Walter as Judith McKnight and Mark Harmon as Leroy Jethro Gibbs

On NCIS's "16 Years" (Season 13, Episode 7), the murder of a retired Navy Lieutenant Commander forces Ducky to reveal his participation in a secret society that solves cold cases.
Michael Weatherly as Anthony DiNozzo, Pauley Perrette as Abby Sciuto, and Sean Murray as Timothy McGee

Michael Weatherly as Anthony DiNozzo, Pauley Perrette as Abby Sciuto, and Sean Murray as Timothy McGee

"16 Years" (Season 13, Episode 7)
Todd Louiso as Lyle Waznicki, Mark Harmon as Leroy Jethro Gibbs, Richard Riehle as Walt Osorio, and Jessica Walter as Judith McKnight

Todd Louiso as Lyle Waznicki, Mark Harmon as Leroy Jethro Gibbs, Richard Riehle as Walt Osorio, and Jessica Walter as Judith McKnight

"16 Years" (Season 13, Episode 7)
Mark Harmon as Leroy Jethro Gibbs, Brian Dietzen as Jimmy Palmer, David McCallum as Donald

Mark Harmon as Leroy Jethro Gibbs, Brian Dietzen as Jimmy Palmer, David McCallum as Donald "Ducky" Mallard, and Emily Wickersham as Ellie Bishop

"16 Years" (Season 13, Episode 7)
Mark Harmon as Leroy Jethro Gibbs, David McCallum as Donald

Mark Harmon as Leroy Jethro Gibbs, David McCallum as Donald "Ducky" Mallard, Michael Weatherly as Anthony DiNozzo, Sean Murray as Timothy McGee, and Emily Wickersham as Ellie Bishop

"16 Years" (Season 13, Episode 7)
Richard Riehle as Walt Osorio and Jessica Walter as Judith McKnight

Richard Riehle as Walt Osorio and Jessica Walter as Judith McKnight

"16 Years" (Season 13, Episode 7)