'NCIS' EPs on Gibbs' 'Worst Nightmare' & New Purpose in the Season 16 Finale

Kate Hahn
Finale Sonja Flemming/CBS

Steely Special Agent Gibbs (Mark Harmon) starts to unravel tonight when a new crime has him reliving the vigilante murder he committed almost 20 years ago: assassinating the man who killed his first wife, Shannon, and young daughter, Kelly.

Now, Gibbs's longtime friend, former FBI agent Tobias Fornell (Joe Spano, above right, with Harmon and Maria Bello), begs Gibbs to help him bring justice to the person responsible for giving his daughter Emily (Juliette Angelo) a near-fatal dose of a date rape drug. 

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"Gibbs did something for his daughter in the heat of the moment. Maybe it's not something he regrets, but it's something he's grappling with," says exec producer Frank Cardea. "Now he might be asked to do that very same thing again."

Guiding Gibbs in his decision is the ghost of his deceased former wife, Diane (Melinda McGraw) — who also happens to be Fornell's ex and Emily's mom. Gibbs has seen and talked to ghosts before, but there's a dark humor to his dealings with this one.

(Sonja Flemming/CBS)

"Diane is his worst nightmare," Cardea says of the woman who drained Gibbs's bank account before leaving him. "And she's got a mouthful to say."

Speaking of the dearly departed, fans have seen shreds of hope this season that agent Ziva David (Cote de Pablo, who left the show in 2013) may actually be alive and return. This after the hidden-away she-shed where Ziva secretly worked on cold cases was discovered.

"We're going someplace [with that story]. We don't really necessarily know where yet, but we're as excited as anyone else to see where it can go," Cardea hints. 

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In the meantime, the finale will reveal a clandestine side project that Gibbs has been working on (it's not another boat!). "Gibbs has been looking for a purpose," teases exec producer Steven D. Binder. "We find out what his purpose will be."

NCISSeason 16 Finale, Tuesday, May 21, 8/7c, CBS