‘Watson’s Latest Episode Just Made Derian Even More Unpredictable

Editor’s Note: The following contains spoilers for Season 1, Episode 9 of Watson

For weeks, Watson has hinted that Dr. Ingrid Derian (Eve Harlow) isn’t exactly who she claims to be, or at least that there’s far more to her story than she lets on. In Episode 9, “Take a Family History,” the show finally delivers on that promise, diving into her traumatic past and long-buried secrets in an emotional gut punch that redefines everything we thought we knew about her. Through a series of flashbacks, we see the trauma, guilt, and complicated love that have shaped Derian into the woman — and the doctor — she is today.

Eve Harlow has been delivering layered, compelling performances all season, but this episode truly lets her shine. As Derian’s past collides with her present, she’s forced to confront both Dr. Watson (Morris Chestnut) and Dr. Morstan (Rochelle Aytes) about the carefully constructed lies she’s told to protect her sister and herself. With everything beginning to unravel and her future on the line, Derian is more unpredictable than ever.

Episode 9 of ‘Watson’ Reveals a History Between Derian and Morstan

The episode opens on New Year’s Eve 2009 and introduces us to a teenage Derian (Amanda Arcuri), who used to go by her nickname, “Didi.” She rushes into the hospital looking for her sister Gigi, who’s just been admitted with a spinal injury after falling from a second-story balcony. In the present day, Derian is caring for the adult Gigi (Kiera Allen), who audiences learned earlier in the season is in a wheelchair and is a candidate for the Spinal Signal Project. She’s suddenly overcome by horrible pain all over her body, and with no other option, Derian brings her to UHOP. But there’s an issue with that — she’s been hiding the fact that they’re sisters so she can secretly fast-track Gigi into the project.

Through more flashbacks, we learn that Didi believed it was their abusive father who caused Gigi’s fall. When she doesn’t feel like the doctor taking care of Gigi is doing the right thing, she seeks out who she’s told is the best surgeon in the hospital: Dr. Mary Morstan, then a young attending surgeon and far from the person in charge. However, she’s the only doctor willing to hear Didi out, especially about the abuse their father inflicts on her and her sister.

After Didi pleads with Dr. Morstan to help her sister walk again, Morstan is moved by her determination and agrees to move forward with the surgery. Just as it’s about to begin, however, it’s abruptly shut down by her superior, who deems it too risky. The moment is quietly devastating, not just for Gigi, who never knew the chance existed, but for Didi and Morstan, who are left feeling powerless. Amanda Arcuri and Rochelle Aytes are excellent in these scenes, capturing the emotional weight of two young women trying to change the outcome but ultimately denied the chance. While present-day Derian hopes to keep her shared history with Morstan a secret, Dr. Watson has already figured her out.

Related

CBS’ New Medical Drama Dethrones ‘Tracker’ for Most Viewers

The Sherlock Homes-inspired series is making waves.

What Does This Revelation Mean for Dr. Derian’s Future in ‘Watson’?

Dr. Derian is devastated when Dr. Watson figures out what she’s been hiding: that her “patient” is actually her sister, Gigi. The revelation makes everything click for Dr. Morstan, who finally realizes that Derian is the same desperate girl from that traumatic night years ago. In one of the episode’s most heartbreaking scenes, Eve Harlow and Rochelle Aytes deliver standout performances as their characters emotionally revisit the past. Morstan admits she never forgot what happened, while Derian opens up about Gigi’s spiral into depression after losing her dream of becoming a ballerina. It’s a gut-wrenching moment but, in true Watson fashion, it leads to a breakthrough in the case.

After successfully treating Gigi’s pain, Derian’s relief is short-lived. She worries Gigi might be removed from the program, but in a moment of compassion, Morstan allows her to stay. This time, she has the power to help, and she refuses to repeat the mistake of doing nothing. However, that’s the only good news Derian gets. Morstan then delivers a crushing blow: she was warned about Derian and now wishes she’d listened. Unless she finds another job within two months, Derian will be fired.

With her future at UHOP hanging in the balance, the stakes have never been higher for the character or the show. Eve Harlow continues to deliver career-best work, embodying every contradiction in Derian’s personality. In this episode alone, she moves through anger, guilt, heartbreak, and tenderness with remarkable nuance. But, there’s one more piece to the puzzle that will add even more to Derian’s character. The final act delivers one more major reveal and reminds us of the looming threat still hanging over Derian: Moriarty (Randall Park), who’s been holding onto her biggest secret of all.

In the final moments, the twist lands: the body Moriarty pulled from the water is Gigi and Derian’s father. Years ago, after Gigi confirmed that he had pushed her, Derian took justice into her own hands. She led him to the water’s edge and injected him with fentanyl. It’s a shocking reveal, but one the show has been building toward all season. What makes it so effective is that it deepens the complexity we’ve come to expect. Derian didn’t kill out of cold blood; she killed to protect herself and the sister she’s spent her life trying to save. Now, with her career on the line and her darkest secret at risk of being exposed, Dr. Ingrid Derian is a wildcard with nothing left to lose. And Watson just made her more dangerous — and more compelling — than ever before.

Watson

Release Date

January 26, 2025

Network

CBS

Showrunner

Craig Sweeny

Directors

Larry Teng

Writers

Craig Sweeny

• 
• 
• 

  Eve Harlow

  Dr. Ingrid Derian

• 

  Inga Schlingmann

  Dr. Sasha Lubbock