The prolific producer said in March that he has an idea for a potential fifth 'Chicago' series. Plus: Watch THR's exclusive video from Wednesday's backdoor pilot for 'Chicago Justice.'

The Chicago franchise isn't showing any signs of slowing down.

The flagship NBC drama, Chicago Fire, launched two spinoffs in its first three years on the air: Chicago P.D. in 2013, followed by Chicago Med last spring. And now the franchise is preparing for another possible growth spurt with Wednesday's backdoor pilot for Chicago Justice.

Although it's a rapid expansion rate for a TV series without source material, the executive producers behind the Windy City-set series say it was only natural.

"It is literally the fourth leg of the table," executive producer Dick Wolf told The Hollywood Reporter at a March PaleyFest event.

The characters of Chicago Justice will be introduced in Wednesday's episode of Chicago P.D. when Officer Burgess (Marina Squerciati) shoots an unarmed teenager after her partner, Roman (Brian Geraghty), is shot and seriously injured in their police car.

Watch The Hollywood Reporter's exclusive video from the tense crime scene below:

Assistant State Attorney Peter Stone (Strike Back's Philip Winchester) then steps in to defend Burgess and conduct his own investigation. However, Stone has some surprising, and complicating, ties to Sgt. Voight (Jason Beghe).

"He's the one that put Voight away in prison. So Voight is at once respectful and yet there's clearly a little bit of ire there," Chicago P.D. showrunner Matt Olmstead told THR last month. "He knows the guy means business because to not be afraid to go toe-to-toe with Voight and win, ultimately you're going to get his respect. There's a nice backstory there."

The episode marks just the second time Chicago P.D. has tackled a legal case – the first being a three-show January crossover where the doctor who helped treat Voight's now-late wife stood trial. However, the legal jargon is old hand for Wolf, who launched the Law & Order franchise in 1990.

"Courtroom machinations are gladiatorial combat in suits and that's endlessly fascinating to me," Wolf said.

Wolf helped craft the story and was on set for the filming of the backdoor pilot. "This was his baby all the way," Olmstead said.

The prolific producer even went so far as to write a Law & Order character into the "Justice" episode. Lorraine Toussaint (Orange Is the New Black) reprises the role of defense attorney Shambala Green which she originated in the first season of Law & Order 26 years ago and played several more times over a 13-year period.

Wolf is open to other possible Law & Order franchise character crossovers should Justice be picked up to series.

"Anybody who has been on Law and Order, SVU, Criminal Intent, is eligible, certainly, to be in Justice because they could have been cops, felons, major case investigators," Wolf said. "There are DA conventions."

Despite their shared DNA, Wolf stressed that the "storytelling is totally different" on Chicago Justice. "It’s a legal show, but its not Law & Order."

In particular, Olmstead points to the Chicago Justice characters, many of which have yet to be developed. The guest cast for the episode will include several other potential series regulars for the spinoff, including Carl Weathers, Nazneen Contractor, Joelle Carter and Ryan-James Hatanaka.

"There's a big growth spurt to speak because whoever the showrunner is or showrunners are come in help define it," Olmstead said, pointing to Chicago Med bosses Diane Frolov and Andrew Schneider, who came onboard several months after the backdoor pilot had already aired during an April episode of Chicago Fire. "We’ve got the right actors, we hopefully gave them the right material."

However, the biggest question on many viewers' minds is whether the courtroom will be the final frontier for the Chicago franchise. After all, most tables only have four legs. But Wolf confirms he already has an idea for a fifth series.

"Yes," he said as a smile splashes across his face. "But I'm not going to tell you what it is."

Viewers will just have to wait and see.

Chicago P.D.'s "Justice" episode airs Wednesday at 10 p.m. on NBC.