Benedict Cumberbatch isn’t the only Sherlock Holmes on-screen. Robert Downey Jr.’s “Sherlock Holmes” franchise is hoping to add a third installment. Producer Lionel Wigram revealed that a movie script is being written.

“We’re working on a 'Sherlock Holmes 3' script,” Wigram told IGN. “I think we would all love to do one if we could come up with something that really was really going to knock it out of the park and was going to be the best of the three. So we’re working on that – it’s quite hard to do.”

Apparently, it’s very difficult because this isn’t the first time a “Sherlock Holmes 3” script has been confirmed. “We had a meeting earlier this year, the three of us,” Jude Law, who plays Watson, told Digital Spy in November 2013. “And I think it's being written now. Warner Bros. have still got to agree to pay for it... I think they want to!”

Downey previously noted that they wanted it to be even better than the first two films, “Sherlock Holmes” and “Sherlock Holmes: A Game of Shadows,” so they were taking their time. “Yes, we have a 'Sherlock 3' in development. We want it to be the best of the series, so that's a pretty tall order,” the “Iron Man” actor told E! Online in November 2014. “Also, Perry Mason is a property I'm looking forward to developing further, going back to the 1931 book series … similarly to what we did with the first 2 'Sherlocks,' mining the original material for things that are ‘new.’”

Wigram confirmed in his recent interview that both Downey and Law are still interested in reprising their roles as Holmes and Watson. “Very. Very,” he said.

Downey got fans excited for a possible sequel earlier this year when he posted a picture on Facebook that looked like it could be from the set of a new “Sherlock Holmes” film. The caption simply said, “Master of disguise…” and that made fans speculate that the movie could be in production. However, it looks like audiences will have to wait a while longer.

A “Sherlock Holmes” sequel seems like a no brainer. The 2009 film made $524 million worldwide, while the 2011 sequel outpaced the first and earned $545 million worldwide, according to Box Office Mojo. However, in addition to script delays, Downey is also busy with another successful franchise. Since the last “Sherlock Holmes” film was released, the actor has played Tony Stark in four different Marvel movies, including the upcoming “Captain America: Civil War.” They’ll likely have to figure out how to work around Downey’s Marvel commitments whenever the script is finished.

No possible release dates for “Sherlock Holmes 3” have been announced. For those looking for an immediate Sherlock Holmes fix, Ian McKellan is playing the famous detective in “Mr. Holmes,” which is in theaters now.