Robert Downey Jr.'s third Sherlock Holmes film aims to kickstart Marvel-style 'mystery-verse'

The Marvel Cinematic Universe's Iron Man took away plenty of lessons from the Disney company's large-scale film plans after solving its Endgame with a snap. Now Robert Downey Jr. is bringing what he learned about massive IP universes to his other giant film franchise: Sherlock Holmes.

While a third movie is on the way, the Guy Ritchie-helmed films (Sherlock Holmes and Sherlock Holmes: A Game of Shadows) never felt overly expansive with its Holmes (Downey Jr.) and Watson (Jude Law) double act. However, that will all be changing with this next entry if Downey Jr. has his say. Speaking at a Fast Company Innovation Festival panel, Downey Jr. and his producing partner/wife Susan Downey explained that Sherlock Holmes 3 is just the entry point for a giant Sherlock universe.

Right, right — there's a Marvel Universe, a DC Universe, a Sony Universe of Marvel characters, a Dr. Seuss Universe...when's enough enough? Well, as the Sherlock portrayer himself clarified, "At this point, we really feel that there is not a mystery-verse built out anywhere, and Conan Doyle is the definitive voice in that arena, I think, to this day." Yeah, there isn't really a "mystery-verse" out there, whatever that means. In Downey Jr.'s eyes, that means opportunity: “So to me, why do a third movie if you’re not going to be able to spin off into some real gems of diversity and other times and elements?”

“We think there’s an opportunity to build it out more,” Susan Downey said. “Spin-off characters from a third movie, to see what’s going on in the television landscape, to see what Warner Media is starting to build out, things with HBO and HBO Max.”

Fans have already seen a bit of this plan put into action with WB's planned The Batman and its Gotham PD-focused HBO Max show. Team Downey wants to try the same multimedia approach with its Sherlock world — and one its producers have been closely following for years over at Marvel.

“I do think that the decade of tutelage and observation, what we were both able to have with Marvel, watching them build out and see all the opportunities, was invaluable. It was like a master class,” Downey said. “And they really did know what they were doing and they had this tight-knit group of people from [the] jump locked into a vision that enables them to broaden” the source material into the cinematic universe.

“What I saw was very humble beginnings, very uncertain outcomes, a lot of creative risk-taking, but there was also an algorithm to the potential,” Downey Jr. recalled. “It’s also having the right people. Different sensibilities will get you to different places downfield.”

Right now the plans for the franchise's solidified next step, a third movie, are still a bit nebulous. Though WB's film schedule has been moving back and forth thanks to the coronavirus, Sherlock Holmes 3 is set for Dec. 2021. No word on when any potential TV or film spin-offs could happen...or whom they might revolve around. These are just the first mysteries of the mystery-verse.