Summary

• Young Sherlock is an Prime Video prequel set in the world of Sir Arthur Conan Doyle's Sherlock Holmes stories.
• The show has cast Dónal Finn as Sherlock's nemesis James Moriarty.
• Finn is best known for his role in the Prime Video fantasy series The Wheel of Time.

Young Sherlock is a Prime Video prequel show created by Matthew Parkhill and directed by Guy Ritchie that is set in the world of the iconic detective stories by Sir Arthur Conan Doyle. Hero Fiennes Tiffin is set to play the title role, bringing Holmes to life during one of his earliest adventures at age 19, while the ensemble cast will be filled out by Natascha McElhone, Colin Firth, Zine Tseng, and Hero's uncle Joseph Fiennes.

Per Variety, Young Sherlock has cast Dónal Finn as James Moriarty. Professor James Moriarty is one of the most iconic characters in the original Doyle stories. The character, who debuted in 1893’s "The Adventure of the Final Problem,” is responsible for the death of the iconic detective and thus is viewed as one of his most prominent enemies.

He has previously been portrayed onscreen multiple times by actors, including Andrew Scott in the show Sherlock and Jared Harris in Sherlock Holmes: A Game of Shadows.

Everywhere You've Seen Dónal Finn Before Young Sherlock

Finn Plays Another Major Prime Video Role.

While the up-and-coming star has a relatively short onscreen resume, Dónal Finn's experience in fantasy shows should help him channel the energy needed to provide the right atmosphere for a period piece.

Because of his titanic stature in the history of Holmes, Moriarty is one of the most important figures in Young Sherlock, especially because the iconic Dr. John Watson likely won't appear in the show. It makes sense that the Prime Video show would want to call upon a known quantity to bring the character to life. Finn fills that need quite well, as he is already well known for portraying Mat Cauthon on the popular Prime Video fantasy show The Wheel of Time.

Sherlock Holmes did not meet his longtime sidekick and chronicler Dr. Watson until he was 27 years old.

Beyond his role in the Wheel of Time cast, Finn has appeared in multiple other major fantasy franchises. This includes playing Nettly on a 2019 episode of Netflix's The Witcher and appearing in the third and so far final Harry Potter prequel Fantastic Beasts and Where to Find Them: The Secrets of Dumbledore in a small role as Albert, an employee at Kowalski Quality Baked Goods. His other most notable roles include appearing in How to Build a Girl, Netflix's Cursed, and BBC One's Rogue Heroes.

While the up-and-coming star has a relatively short onscreen resume, Dónal Finn's experience in fantasy shows should help him channel the energy needed to provide the right atmosphere for a period piece. On top of his fantasy roles, he also has ample experience on the stage, including starring in Chasing Bono at London’s Soho Theatre. This should all give him the appropriate dramatic grounding to play a key character in the overall Holmes mythos like Young Sherlock's aged-down Moriarty.

Source: Variety