Set in the 19-year gap between the prequel and original movie trilogies, Underworld was the working title for a proposed television series that would focus on all-new characters while still filling in pieces of the core backstory of the original movies. George Lucas announced the project during celebrations for the 30th anniversary of the franchise at Star Wars Celebration III in 2005, telling fans that he planned to "get it started and hire the show runners and all of that, then I'll probably step away."

As to what the series would be about, that was always somewhat nebulous. Lucas teased that the stories would be "a little bit more adult" than the movies, and offer "something most people have never seen on television before."

Producer Rick McCallum would, years later, echo those sentiments in a 2012 interview, calling it "much darker" and "a much more adult series" than the movies. "If we can ever get it together and George really wants to pursue it, it'll be the most awesome part of the whole franchise, personally," he said, calling it "Empire [Strikes Back] on steroids."

(Later reports would suggest that the series would focus on criminals on Coruscant — the Empire's home world from Star Wars: Episode III — Revenge of the Sith — with "rival families struggling for control of the seedy underside of the Star Wars universe." A bounty hunter was rumored to be the series lead, with many fans believing that to mean a young Boba Fett, introduced in Star Wars: Episode II — Attack of the Clones.)

Plans for the series seemed to continually be in flux; McCallum referenced "somewhere like 100 hours" being planned in 2005, but two years later had changed that to "up to 400 episodes." Part of that seeming confusion might have stemmed from Lucas' 2007 comments that the series was actually "one show that will split into four shows, focusing on different characters," while continuing to build out the Star Wars universe.

Many writers were approached to contribute to the series, with Lucas intending to have as many episodes written ahead of production as possible. Among those approached were Battlestar Galactica's Ronald D. Moore, who did in fact contribute to the show, and Doctor Who's Russell T. Davies, who revealed in the book Doctor Who: The Writer's Tale that he'd turned down the opportunity to continue working on the BBC science fiction series.

As of 2010, scripts for 50 episodes (and an additional "movie of the week") had apparently been completed, along with more than a year of design work, but production on the series was delayed because the series would have been too expensive to shoot in its current incarnation.

"We can't figure out a way of doing it for under $50 million an episode," Lucas told IGN. "I'm not going to compromise on the quality of it, so we just have to keep working on the technology to see if we can improve ways of getting the story told without it costing a fortune."

A potential solution was Grady Ranch, a planned expansion to Lucas' Lucas Valley property intended to act as a "digital media production facility for movies and television," but that project was delayed — and ultimately abandoned — because of objections by nearby residents and environmentalists concerned about an increase in traffic to the location.

The series went dormant because of its scale, but as recently as 2013 remained a potentially ongoing interest, with ABC reportedly looking at adding a version of the series to its lineup.

With the 2014 reorganization of Star Wars canon — not to mention Disney's plans for a new Star Wars feature every year, including some set in the same time period as Underworld — it was assumed that the show had finally, quietly, been abandoned.

That is, until Kennedy offhandedly noted to Slashfilm that the Lucasfilm story team have "spent a lot of time reading through the material that he developed," going on to call it "gold" and adding "it's something we're spending a lot of time looking at, pouring through, discussing, and we may very well develop those things further."

Will Underworld survive its near-death experience and make it to the small screen? Perhaps not, unless someone has worked out a way to make it far cheaper than Lucas initially anticipated.

But there is an alternative: what if the stories created for the show were retrofit to become movies in their own right, for release after the already announced Star Wars: Rogue One and unnamed young Han Solo movie? With 50 hours of material already written (and partially-visualized), it has to be a tempting option for Lucasfilm, which is already contracted to produce a new feature annually starting with next week's big release.

Could the future of Star Wars' hidden history end up showing up on the big screen years from now? Fans will inevitably hold out hope for this possibility, but for now, only the Force — and Kathleen Kennedy — can say.