Nicola Walker has carved out an illustrious career as one of Britain’s most versatile and compelling actresses, particularly in the realm of crime dramas. Her ability to bring depth, nuance, and humanity to complex characters has made her a standout in a crowded field of television talent. From her early roles in Spooks to her recent work in The Split and Annika, Walker has consistently delivered performances that resonate with audiences and critics alike. Among her many roles, two detective characters stand out: DI Annika Strandhed in Annika and DCI Cassie Stuart in Unforgotten. While Annika has garnered praise for its unique style and Walker’s magnetic performance, it is Unforgotten—and specifically her portrayal of Cassie Stuart—that represents the pinnacle of her detective roles. This article explores why Unforgotten is Nicola Walker’s best detective show, delving into the show’s narrative strength, her exceptional performance, and its lasting impact on the crime drama genre.

The Rise of Nicola Walker in Crime Dramas

Nicola Walker’s journey in television began in the 1990s, with roles in shows like Spooks, where she played the intelligence analyst Ruth Evershed. Her ability to portray characters with emotional depth and intellectual sharpness quickly made her a favorite among viewers. Over the years, she has taken on a variety of roles across genres, from legal dramas like The Split to heartfelt family stories like Last Tango in Halifax. However, it is in the crime drama genre that Walker has truly shone, taking on no fewer than eight different police or detective roles in British television.

Her performances in shows like River, where she played the ghostly DS Jackie ‘Stevie’ Stevenson, and Touching Evil, where she portrayed the no-nonsense DI Susan Taylor, have demonstrated her range. Yet, it is her work in Unforgotten and Annika that has sparked the most discussion among fans and critics. Both series showcase her ability to embody complex, layered detectives, but they differ significantly in tone, style, and emotional weight. To understand why Unforgotten stands out, we must first examine the unique qualities of both shows and Walker’s contributions to them.

Annika: A Fresh Take on the Crime Drama

Annika, which first aired on Alibi in 2021 and later on BBC One in 2023, is a distinctive addition to the crime drama genre. Based on the BBC Radio 4 drama Annika Stranded, the series follows DI Annika Strandhed, a Norwegian detective leading the Marine Homicide Unit (MHU) in Glasgow. The show is set against the backdrop of Scotland’s waterways, where Annika and her team investigate brutal and often perplexing murders. The series is notable for its blend of dark crime stories and a lighter, almost whimsical tone, largely due to Walker’s performance and the show’s stylistic choices.

One of Annika’s defining features is its use of the fourth-wall-breaking technique, where Annika directly addresses the audience, sharing her thoughts on the cases and her personal life. This approach, reminiscent of Fleabag or Chewing Gum, adds a layer of intimacy and humor to the series. As The New York Times noted, Walker’s ability to convey “the emotions lurking beneath self-consciousness and awkwardness” makes this narrative device not only tolerable but engaging. Her wry observations and sharp wit bring a freshness to the genre, setting Annika apart from more traditional police procedurals.

The series also benefits from strong ensemble performances, with actors like Jamie Sives as DS Michael McAndrews and Katie Leung as DC Blair Ferguson adding depth to the team dynamics. The second season, which aired on BBC One on August 2, 2025, introduced new cast members like Varada Sethu as DS Harper Weston and continued to explore complex cases, such as a body found in a dog cage or encased in ice. Viewer reactions have been overwhelmingly positive, with many praising Walker’s “marvellous” performance and the show’s blend of humor, drama, and relationships. One fan described Annika as “brilliant—funny, dramatic, and ‘relationship-y,’” highlighting its broad appeal.

Despite its strengths, Annika is not without flaws. The fourth-wall-breaking can occasionally feel gimmicky, and the show’s lighter tone sometimes undermines the gravity of its murder investigations. While Walker’s performance is undeniably captivating, the series leans heavily on her charisma to carry its more unconventional elements. For some viewers, this makes Annika a refreshing change of pace, but for others, it lacks the emotional depth and narrative heft of other crime dramas. This is where Unforgotten distinguishes itself, offering a more grounded and emotionally resonant experience.

Unforgotten: A Masterclass in Cold-Case Drama

Unforgotten, created by Chris Lang and first aired on ITV in 2015, is a cold-case crime drama that follows DCI Cassie Stuart and DI Sunny Khan (Sanjeev Bhaskar) as they investigate long-buried murders. The series, which ran for four seasons with Walker in the lead role, is renowned for its meticulous storytelling, realistic character development, and emotional depth. Each season focuses on a single case, unraveling secrets that have lingered for decades and exploring their impact on victims, families, and communities.

Walker’s portrayal of Cassie Stuart is the heart of the series. Cassie is a detective of supreme empathy, balancing a sharp intellect with a deep concern for justice and the human cost of crime. Unlike the often stereotypical “tortured detective” trope, Cassie is a fully realized character—a professional who is competent and compassionate, yet burdened by the emotional toll of her work. Walker’s performance is a masterclass in subtlety, conveying Cassie’s resilience and vulnerability through understated gestures and expressions. As The Killing Times noted, her portrayal is “deeply humane,” making Cassie a standout in a genre often dominated by male detectives.

The series’ strength lies in its ability to weave together past and present, showing how historical crimes ripple through time. For example, Season 2 explores the murder of a Conservative Party consultant found in a suitcase, while Season 4 investigates a headless corpse discovered in a freezer. These cases are not just puzzles to be solved but opportunities to examine themes like grief, betrayal, and societal change. The show’s thoughtful pacing and focus on character-driven storytelling set it apart from flashier crime dramas, and Walker’s chemistry with Bhaskar adds a layer of authenticity to their partnership.

Unforgotten has been lauded for its emotional impact and realistic portrayal of police work. Reviewers have called it “gripping” and “outstanding,” with Walker’s performance often singled out for praise. One viewer described her as conveying “compassion and sympathy” that is “felt” rather than just seen, emphasizing the emotional weight she brings to the role. The series’ ability to handle sensitive topics, such as online trolling or flawed police investigations, further enhances its relevance and resonance.

Comparing Annika and Unforgotten

While both Annika and Unforgotten are excellent crime dramas, they cater to different sensibilities. Annika is lighter and more stylized, with its fourth-wall-breaking and scenic Scottish backdrop creating a distinctive vibe. It’s a show that doesn’t take itself too seriously, allowing Walker to showcase her comedic timing and charm. However, this lighter tone can sometimes dilute the stakes of its murder investigations, making it feel less grounded than Unforgotten.

In contrast, Unforgotten is a slow-burn drama that prioritizes emotional authenticity and narrative depth. Its focus on cold cases allows for a richer exploration of human experiences, from the pain of unresolved loss to the moral complexities of justice. Walker’s Cassie Stuart is a more fully developed character than Annika Strandhed, with a personal life—complete with family struggles and romantic prospects—that adds layers to her professional role. The show’s ensemble cast, including guest stars like Alex Jennings and Neil Morrissey, further elevates its storytelling.

Walker’s performances in both shows are exceptional, but her work in Unforgotten stands out for its emotional range. In Annika, she leans into the character’s wit and unpredictability, breaking the fourth wall to create a direct connection with the audience. In Unforgotten, she delivers a quieter, more introspective performance, capturing Cassie’s inner turmoil and moral conviction. The latter role demands a level of subtlety and emotional intelligence that showcases Walker’s full range as an actress.

The Legacy of Female Detectives

Unforgotten also holds a special place in the crime drama genre for its contribution to the portrayal of female detectives. As Digital Spy notes, Cassie Stuart is part of a lineage of complex, powerful women in the genre, alongside characters like Jessica Fletcher, Jane Tennison, Catherine Cawood, Marcella, and Stella Gibson. These characters have redefined the archetype of the detective, moving away from the male-dominated narratives of the past. Cassie, in particular, stands out for her empathy and humanity, qualities that Walker imbues with authenticity.

When Walker left Unforgotten after its fourth season, fans were devastated, questioning whether the show could continue without her. Sinéad Keenan stepped into the role of DCI Jessica James, bringing a new dynamic to the series. While Keenan’s performance was well-received, it underscored the unique space Walker had carved out as Cassie. The transition highlighted the importance of not pitting female actors against one another but recognizing the distinct contributions each brings to the genre.

Why Unforgotten Reigns Supreme

Ultimately, Unforgotten is Nicola Walker’s best detective show because it combines her finest performance with a narrative that is both emotionally compelling and intellectually engaging. The series’ focus on cold cases allows for a deeper exploration of human stories, making it more than just a procedural. Walker’s portrayal of Cassie Stuart is a career-defining role, showcasing her ability to convey complex emotions with subtlety and grace. The show’s critical acclaim, viewer devotion, and lasting impact on the crime drama genre cement its status as a standout in Walker’s oeuvre.

For fans of Annika who haven’t yet watched Unforgotten, the series is a must-see. Available on ITVX, Netflix, and Disney+, it offers a binge-worthy experience that highlights Walker at her best. While Annika is a delightful and innovative crime drama, Unforgotten is a masterwork that captures the heart and mind, thanks to Walker’s unforgettable performance as DCI Cassie Stuart.