“Sherlock Holmes 3” has a mystery so difficult that an extra pair of hands are needed to solve it. The film has hired a new screenwriter to rework the script. James Coyne will pen Robert Downey Jr. and Jude Law’s next adventure.

James Coyne replaces Drew Pearce, Deadline reports. The “Iron Man 3” writer was hired in 2011, just before “Sherlock Holmes: A Game of Shadows” was released. However, in late 2015, producer Lionel Wigram confirmed that the third film’s script was still unfinished.

“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.”

The team likely wants to improve the critical reception of “Sherlock Holmes.” According to Rotten Tomatoes, the second film, “Sherlock Homes: A Game of Shadows,” wasn’t as well received as the first, especially among top critics. Reviews aside, it seems like everyone involved wants to make a third film. The 2009 film brought in $524 million while the second earned $545 million worldwide, Box Office Mojo reports.

Luckily, Downey has plenty of work to keep him busy while Coyne perfects the script. His Marvel commitments take up a good portion of his schedule. He is currently promoting “Captain America: Civil War,” and he is set to appear in “Spider-Man: Homecoming.”

Guy Ritchie will direct “Sherlock Holmes 3,” and Ritchie/Wigram Productions, Team Downey, Silver Pictures and Warner Bros. are producing. The film does not have a release date yet.