Complete cast breakdown of Watson season 2: Who plays who & where you’ve seen them before

On November 10, 2025, CBS will air Watson season 2 Episode 5 at 10 p.m. ET. The second season of CBS's unique adaptation of Arthur Conan Doyle's Sherlock Holmes stories follows Dr. John Watson, a medical detective at the Holmes Clinic of Diagnostic Medicine.

Dr. Watson solves medical cases using his deductive skills this season. He uses deductive reasoning he learned from Sherlock Holmes, to help his patients. The story explores his complicated marriage to Dr. Mary Morstan and his relationships with coworkers. Watson season 2 also stars Ingrid Derian, Shinwell Johnson (Ritchie Coster), and Sherlock Holmes.

Watson season 2: Main cast breakdown

Morris Chestnut as Dr. John Watson

Morris Chestnut plays the role of Dr. John Watson, a former London-based consulting detective-turned-head of the Holmes Clinic of Diagnostic Medicine.

Watson solves complicated medical mysteries using deductive reasoning he learned from Sherlock Holmes. 

First known for Boyz n the Hood (1991), Morris later starred in The Best Man, Ladder 49, The Game Plan, and Kick-Ass 2. Chestnut appeared in V, Rosewood, Nurse Jackie, Goliath, and The Resident. Nurse Jackie and The Best Man: The Final Chapters earned him NAACP Image Award nominations and wins.

He adds more clarity to Dr Watson's character in Watson season 2, continuing his success.

Eve Harlow as Ingrid Derian

Eve Harlow plays mysterious neurologist Ingrid Derian. Ingrid's coldness and controversial methods irritate coworkers. Harlow is a veteran actress who appeared in The Killing, Titans, and The Haunting Hour: The Series.

Harlow, born in Moscow and raised in Canada, has appeared in US and Canadian films.

Her versatility and portrayal of Ingrid Derian in Watson season 2 add intrigue to the Holmes Clinic. 

Peter Mark Kendall as Stephens Croft & Adam Croft

Stephens and Adam Croft are played by Peter Mark Kendall. They are identical twin brothers who work as specialists in infectious diseases and functional medicine. Stephens, who went to Johns Hopkins, is emotionally distant, while Adam, who went to Boston University, talks too much.

Adam's relationship with Stephens' ex-fiancée makes their already troubled relationship even worse. Kendall has played parts in The Americans, Strange Angel, and The Leftovers.

Kendall, who is known for having a strong stage presence and playing characters well, makes the Croft twins seem real.

His career is varied and includes work on Broadway and TV shows. 

Ritchie Coster as Shinwell Johnson

In Watson season 2, Ritchie Coster plays London criminal Shinwell Johnson, who had a complicated relationship with Dr. John Watson and Sherlock Holmes.

Shinwell becomes a trainee nurse this season after leaving the Holmes Clinic as an administrator. His criminal past and medical transformation add intrigue to the show.

Coster is a versatile English actor with film and TV credits. The Dark Knight (2008) as the Chechen, Blackhat (2015) as Elias Kassar, and True Detective (2015) as Mayor Austin Chessani are his best-known roles.

Law & Order, Happy!, and The Tuxedo (2002) are among his many TV roles.

Rochelle Aytes as Mary Morstan

Rochelle Aytes plays Dr. Watson's ex-wife Mary Morstan. Mary is Watson's anchor and restores normalcy despite their troubled marriage.

Aytes starred in Mistresses (2013-16), Criminal Minds, The Best Man Holiday, and S.W.A.T. Left 4 Dead 2's Rochelle was voiced by her in the video game.

Aytes works in television, film, and voice acting, and her portrayal of Mary Morstan adds emotion to Watson season 2.

Inga Schlingmann as Dr. Sasha Lubbock

Inga Schlingmann plays Dr. Sasha Lubbock, an immunology and rheumatology specialist who is torn between her Chinese biological family and her Dallas adoptive family.

So Help Me Todd (2022) and Law & Order: Special Victims Unit (1999) star Schlingmann gives her character a grounded, empathetic energy.

Her television roles have established her as a strong actor, and in Watson season 2, she shows her range while navigating her character's complex heritage and professional life.

Supporting cast

• Amanda Crew as Lauren (Ex-girlfriend of Stephens)
• Tika Sumpter as Laila Bynum (Pediatric oncologist)
• Robert Carlyle as Sherlock Holmes (Consulting detective)
• Noah Mills as Beck Whyte (Exiled tech worker)
• John Cassini as Ivan Ferry (Group therapist)
• Juanita Jennings as Elizabeth Morstan (Mary’s mother)
• Khary Payton as Miles McClung (Mary’s older brother)
• Tzi Ma as Jun (Sasha’s birth uncle)
• Clarke Peters as Hamish Watson (John’s estranged father)

Watson season 2 is available to stream on CBS.