Prime Video’s newest big show is almost here, and it’s putting a fresh face on one of the most famous detectives ever. Young Sherlock, directed by Guy Ritchie, will show us the early life of Sherlock Holmes long before he lived on Baker Street. The series is set to premiere all eight episodes on March 4, 2026.
This new show is based on the popular book series by Andrew Lane and takes us back to the 1870s. It follows a 19-year-old Sherlock who gets caught up in a dangerous murder case while at Oxford University. He’s not the polished genius yet; he’s described as a “disgraced young man – raw and unfiltered”. This first case pulls him into a worldwide conspiracy that will change his life forever.
With an exciting cast bringing this story to life, here is your complete guide to who’s playing who in Young Sherlock.
Hero Fiennes Tiffin Leads as the Young Detective
At the center of the show is Hero Fiennes Tiffin, stepping into the iconic role of a teenage Sherlock Holmes. At 19 years old, this Sherlock is an unruly student at Oxford University, getting involved in his very first major investigation. Fiennes Tiffin is best known for playing Hardin Scott in the After film series and a young Tom Riddle in Harry Potter and the Half-Blood Prince.
Fans of Guy Ritchie’s previous movies will see a familiar style. The director, who made the hit Sherlock Holmes films with Robert Downey Jr., is returning to the character. Fiennes Tiffin has worked with Ritchie before on The Ministry of Ungentlemanly Warfare and has spoken about the experience. He told Collider, “He’s so decisive and so good at what he does, it’s easy to trust him”. Fiennes Tiffin also shared that the challenge of the role is balancing who Sherlock is now with who he will become, saying, “It’s about getting the measurements right on how much of Sherlock to put in there and how many glimpses to put in of who Sherlock is going to become”.
Meet Sherlock’s Family and Key Allies
A big part of this origin story is introducing Sherlock’s family, who play important roles in shaping the young man.
- Joseph Fiennes plays Silas Holmes, Sherlock’s adventurous father. In a fun real-life connection, Joseph Fiennes is the uncle of the show’s star, Hero Fiennes Tiffin. Joseph is widely recognized for his role as Commander Waterford in The Handmaid’s Tale.
- Playing Sherlock’s mother is Natascha McElhone. Her character, Cordelia Holmes, is described as artistic. McElhone’s recent work includes a role in the series Halo.
- Sherlock’s famously clever older brother, Mycroft, will be portrayed by Max Irons. The character is known for being even more intellectually gifted than Sherlock and often involved in government affairs. Irons has starred in shows like Condor and The White Queen.
The cast also features some major names in key supporting roles. Colin Firth joins the series as Sir Bucephalus Hodge, an Oxford figure who is sure to influence the young Sherlock. Furthermore, Zine Tseng, known from 3 Body Problem, plays Princess Gulun Shou’an, a Chinese princess, scholar, and martial artist who becomes part of Sherlock’s early adventures.
A Young James Moriarty and Other Important Figures
One of the most interesting parts of this prequel is seeing the early days of Sherlock’s relationships, especially with his future nemesis.
- Dónal Finn takes on the role of a young James Moriarty. This character will eventually become Sherlock’s arch-enemy, but the series will explore their initial interactions. Finn is known for playing Mat Cauthon in The Wheel of Time.
- The show also includes a character who seems to be an early investigative contact. Simon Delaney appears as Detective Fitget.
The story expands beyond Oxford with a global conspiracy. Other cast members include Numan Acar as Esad and Ravi Aujla as Kishmore Malik. Rachel Shelley plays Mrs. Anna Tilcott, and Adam James is Dr. Charles Maltby.
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Behind the Scenes of the Prime Video Series
The project is a major production for Prime Video. The series was created for television by showrunner Matthew Parkhill, who also serves as an executive producer. Guy Ritchie, who directs the first two episodes, leads a team of executive producers that includes the original book author Andrew Lane.
Filming for the eight-episode season took place across several locations, giving the story its global scale. Production started in the United Kingdom in July 2024, with scenes shot in Bristol and later in Cardiff, Wales. The crew also filmed on location in Spain, using the cities of Jerez, Cádiz, and Seville to stand in for other parts of the world.
Young Sherlock will be available to stream in more than 240 countries and territories when it launches on March 4, 2026.
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