The studio is keen to get the movie - starring Robert Downey Jr as the titular British detective with Jude Law as Dr John Watson - off the ground and has enlisted some top talent to get the script in shape.
Variety reports that 'Guardians of the Galaxy' writer Nicole Perlman, 'Baywatch's Justin Malen, 'Rogue One's Gary Whitta, 'Tomb Raider's Geneva Dworet-Robertson and 'Snowden' screenwriter Kieran Fitzgerald are all working on the script.
Meanwhile, Robert recently insisted he "can't wait" to make 'Sherlock Holmes 3' as he loves working with director Guy Ritchie and co-star Jude.
He said: "We're talking about it right now. Now! I can't wait. We can do some preliminary stuff. If we could shoot it on Skype we could have done it in a week. I know Guy Ritchie loves me as much as I love him - and he damn well should. When we're making those 'Sherlock' movies it is off the hook. We'll attempt to make one this year. It really is a big deal to go and do those movies. I'm tired all the time, but I'm excited about it."
Downey, who stars as Iron Man / Tony Stark in the Marvel 'Avengers' franchise, is always itching for fresh acting challenges but admits he has to limit his work schedule in order to keep a balance between his career and his private life.
The Hollywood superstar - who is married to producer Susan Downey and has three children from two relationships - said: "I'll get a little itchy here and there. But [the Marvel Universe] makes such a big splash that it keeps the pulse of any relevance going. Truth be told, I like working, but there's so many things I like to do. I have kids. I'm a martial artist. I've been working since I was a kid, so sometimes I do get itchy, but I get a week off and it's pleasant. It's a manageable schedule."