Once upon a time an author wrote crack fics of a tv show devised by Tony and Jimmy (Hysteria, Hysterical, Outrageous!) and then took a tangent with a 'sweeps special' (ZCIS, ZCIS To Be Continued). Parts of this may make more sense if you read those first or... may not.

ZCIS THE UNDEAD REUNION MOVIE.

"This place always gave me the chills" the ghost of Mike Franks observes as it glances around Autopsy.
"It can get a bit cold in here" Palmer responds from where he is seated on the autopsy table.
"Yeah. That's the problem." Mike and Tony share an eye roll from their chairs beside the desk.
"Are you sure there's nothing we can say to make you return for the ten year reunion special?"
"Thanks for the offer DiNozzo. I know a movie may excite the fans but even all these years later I'm still making more than enough money from the show being in syndication to keep me in bad tequila and good women...or do I mean good tequila and bad women?" He chuckles. "I think Gibbs needs a new ghost conscience anyway. Have you thought about Diane? That would shake things up. She's quite a little firecracker. The probie and his redheads..." He chuckles again.
"Good idea." Jimmy hops off the table and comes over to shake ghost Mike's hand. After shaking Tony's too Franks leaves.

"Another thing to cross off our to do list gremlin." Tony sighs. "It would've been fun having him around. Remind me where we're at."
Jimmy swipes through a few pages on his tablet stopping now and again to read something.
"Some time today would be good."
Palmer glares at his partner whom Breena had started calling his work husband at one point early in the development of the new show.
"Sorry."
"We've signed up all the un-dead who were killed in the various shows over the years to fill support roles, sing in the choir and of course be corpses in the big cemetery scene. There was a slight problem with that last but it's been fixed now."
"What was the problem?"
"A few were complaining about being typecast. Since their exposure from this show will be huge they wanted something that would showcase the variety of their talent."
"Huh."
"I just told them there were plenty more corpses out there I could cast." Jimmy grins.

"And where are we with the stars?"
"Almost everyone from the original team is on board. Tim, Abby, Bert, Dr Mallard, Vance, Kate, Paula Cassidy, Chris Pacci, Hall and Nelson, Gibbs although that reminds me..."
"The problem with the Annex Principle II. The half-robot caterpillars. Did the crew get it sorted?"
Jimmy smiles. "Turns out it was rust. The mounted division will ride again."
"And what about our new additions?"
"Jenny Shepard, Jackie Vance and Eli David are all keen to be involved. We've set up meetings for them with the writers to discuss potential ways to include them in the story line."
"Good. Good." Tony frowns as he runs through ideas in his head. Jimmy returns to consulting his tablet. "Wait a minute. You said almost all the original team. Who are we still missing?"
Palmer just stares at him as DiNozzo realizes who is yet to be accounted for.
"Re-ah-lly."
"Yep." Jimmy glances around the room reluctant to meet Tony's eyes as he continues. "I've set up a meeting. " He looks at his tablet again. "In fact she should be here any minute and..." He is interrupted by the doors swishing open and their old colleague entering the room.
"Jimmy."
"Ziva. Take a seat please."
She smiles and sits. "Hello Tony."
"Hello."
There is an awkward silence for a moment as none of them know quite how to start the conversation they need to have.
"I guess you have some questions for me." She smiles.
"Yes, yes we do. The first and most important is...what I meant is...well obviously..." Tony stutters.
"Can you prove you are UN-DEAD?" Jimmy blurts out.

They start to laugh and with a phoof it was time for the ad break.