Everything to Remember Ahead of 'Unforgotten' Season 6

One of PBS Masterpiece's most successful series, Unforgotten, was initially commissioned by ITV in 2014 as a joint project from screenwriter Chris Lang (I, Jack Wright) and director Andy Wilson (Ripper Street). The first season aired in October 2015, and Season 2 in 2017, earning BAFTA nominations and securing distribution on PBS. Seasons 1 and 2 as a set, airing them as six feature-length episodes in 2018 and introducing audiences to DCI Cassie Stuart (Nicola Walker), who had just taken over a new division dedicated to bringing justice to cold cases with her new bagman, DS Sunil "Sunny" Khan (comedian Sanjeev Bhaskar in a rare serious role),

Season 1's "The Case of Jimmy Sullivan" featured the teenager's skeleton in the foundations of the former Arlingham House, dated to the early 1970s, when his mother, Maureen (Frances Tomelty), lost track of him. Cassie identified four suspects: Father Rob Greaves (Bernard Hill), Lizzie Wilton (Ruth Sheen), Sir Phillip Cross (Trevor Eve), and Eric Slater (Tom Courtenay). 

Greaves, the pastor, was sleeping with an underage girl. Lizzie, a skinhead's girlfriend, liked Jimmy but was pressured to beat him up. Cross, now a politician, was a gangster's heavy to whom Jimmy was in debt. Eric, a paraplegic since an 80s car crash, with a wife, Claire, suffering from dementia, was the former bookkeeper.

Cassie and Sunny's no-stone-unturned methods ruined lives. Father Rob revealed a daughter by his teen lover, whom he had embezzled the church funds to care for, destroying his life and family. Lizzie, now married to a Black man, mentoring Black youths, was rejected by her found family and attempted suicide. Cross's political ambitions were derailed. (Ok, that was good.) But the killer was Claire. She suffered post-partum psychosis and targeted her closeted husband's lovers in her rage at his constant cheating. (The car crash was his failed suicide attempt.) Eric, who abused Claire for years, wound up in jail, leaving her in the care of her abusive son, whom she no longer recognized.

That extremely distressing ending (and Cassie's pride at destroying the lives of these old people in the name of "justice") was thankfully followed directly by Season 2, a far more satisfying story. "The Case of David Walker" began with the body of Walker, only 25 years old, who drowned in 1990. His widow, Tessa (Lorraine Ashbourne), a detective herself, was one of the suspects, along with three others: teacher Sara Mahmoud (Badria Timimi), housewife Marion Kelsey (Rosie Cavaliero), and LGBTQ lawyer Colin Osborne (Mark Bonnar), who was trying to adopt with his husband.

Walker, it turned out, was a bastard who peddled orphaned and poor children for sex, the discovery of which drove Tessa to become a cop and the revelation of which ended her career. Sara, Marion, and Colin were all victims of sexual abuse; Sara, a Walker victim, now a devout Muslim, was rejected by her community. Marion, abused by her father, joined the IRA in rebellion; the PTSD that the case provoked shattered her marriage. Colin, abused by a family friend, had his anger issues resurface, derailing the adoption. But, as impossible as it seemed, Cassie learned all three of them did it, each killing the other's abuser, an almost perfect crime until Walker's body surfaced.

When she tracked the three down to a pub where they were meeting up, Colin stood for their defense, convincing Cassie that ruining their lives for the death of monsters was not justice. Ultimately, she let them walk free to go and try to rebuild their lives. Sara was taken back by her husband; Marion stood up to her mother and sister, who had denied the truth for so long, winning back her husband, while Colin finally got help for his anger. But Cassie, lying to Sunny that the trail had run cold, was shaken to the core that her ideas of justice were not as crystal clear as she once believed.

Season 3's body was found in a motorway median, a teen girl, in "The Case of Hayley Reid," missing since New Year's 2001, 18 years ago. Her twin sister (Bronagh Waugh) said she went to a party and never came home. The four suspects were introduced from the start as lifelong best friends, and had rented a house with their wives for a New Year's bash, located around the corner from the pub where she worked. BBC presenter James Hollis (Kevin McNally), lawyer Tim Finch (Alex Jennings), and failing businessman Pete Car (Neil Morrissey) still stayed in touch to help their friend, ex-tech innovator Chris Lowe (James Fleet), whose mental health issues left him homeless.

Hollis, whose relationship with his ex-wife and trans daughter had him on edge, lost his career; Lowe's barely controlled issues were triggered hard due to having his career already derailed once by false accusations. But Cassie's carelessness in losing a file at a tea shop led to Carr being falsely identified as the killer and being murdered by an internet vigilante. Cassie found the real murderer was Finch, a psychopathic manipulator and abuser, and got him put away for life. However, the case left her feeling like her life's work wasn't worth the pain it caused. Although Sunny started a relationship with Sal (Michelle Bonnard), Cassie turned down ex-DCI John Bentley (Alastair MacKenzie) when he asked her out.

Season 4 began with Cassie trying to retire, as Bentley finally got her to start a relationship. She was also angry at her father, Martin, and his growing dementia, blaming his partner, Jenny, and straining the relationship with her son, Adam. But the system forced her to stay one more year. Her final case, "The Case of Matthew Walsh," ultimately proved to be an internal matter. Two suspects were Cassie's peers: DCC Liz Baildon (Susan Lynch) and DCI Ram Sidhu (Phaldut Sharma). The others, Dean Barton (Andy Nyman) and Fiona Grayson (Liz White), were former police officers who left the force shortly after graduating. The four had been BFFs 30 years ago as rookies and covered up Walsh's death. 

Barton was now a smuggler, funding his disabled son's charity; Grayson was hiding the fact that her drunk driving had killed a man, not long after the original incident, which Baildon helped her cover up. However, Cassie never got to see their lives and careers crumble, as she was killed by a drunk driver herself on her way home from work late one night, leaving her family devastated. The team Cassie slowly built over the seasons, DC Jake Collier (Lewis Reeves), DS Murray Boulting (Jordan Long), DS Fran Langley (Carolina Main), DC Katz Wilis (Pippa Nixon), and Dr. Leanne Balcombe (Georgia Mackenzie), were also traumatized. 

Sunny was left to pick up the pieces as Collier moved on. The rest banded together in Season 5 to meet their new boss, who was not the same as the old boss, DCI Jessica James (Sinead Keenan). James was already having a bad day, having learned that her husband Steve (Andrew Lancel) had cheated on her with her younger sister, something their mother Kate (Kate Robbins) seemed to think was a forgivable act. Between that and the hostile situation at work, where Sunny essentially ran "The Case of Precious Falade" without her approval, it made for a very awkward and unpleasant start.

At first, James declared the case "too old" for the underfunded division, until Sunny proved that the body was from 2016, and still within the present-day case limits. Like Season 1, the suspects ran the gamut, seeming completely unrelated: Tory MP Lord Anthony Hume (Ian McElhinney); Karol Wojski (Max Rinehart), a Jewish ex-pat living in France; a small-time thief and drug addict, Royce (Rhys Yates); and Precious' mother, restaurateur Ebele Falade (Martina Laird). However, Hume raped Ebele's mother at 19, fathering Ebele, and Royce was Precious's son, Ebele's grandson, and Hume's great-grandson. Wojski was the social worker; Precious's death was the catalyst for him to quit his career and the country.

However, when Sunny's fiancée leaves him, he and Jessie bond over their disastrous lives and lose themselves in solving the case. Unfortunately (again, much like Season 1), the conclusion was more horrifying than just. Hume claims he went to see Precious and her son, but the son threatened him and, in the scuffle, Precious accidentally shot him, and then turned the gun on himself. Royce, who turns out to have been her other child whom she never allowed to be publicly recorded for fear of having him taken into care, stole his older brother's identity after they died. He claims he was in the house that night, hiding upstairs, and saw Hume shoot both his brother and his mother.

Hume does not dispute Royce's account and is taken to jail, but when Ebele comes to introduce herself to him as his grandmother, he boasts that it was all a lie; Hume had been telling the truth. Precious accidentally shot her son and then committed suicide. But since it was Hume's original sin of rape that started all this, Royce declares it justice that the aristocrat be the one to pay. 

Is it justice? It's hard to say. But with Jessie and Sunny now a team, Season 6 looks to be another interesting case, either way.

(The post was originally published 08.26.23. Updated 8.20.25)

Unforgotten Season 6 premieres on most local PBS stations, the PBS app, and the PBS Masterpiece Prime Video Channel beginning Sunday, August 24, 2025, at 10 p.m. ET, directly following the premieres of Professor T Season 4 at 8 p.m. and The Marlow Murder Club Season 2 at 9 p.m. All six episodes of Season 6 will be available for members on premiere day via PBS Passport. As always, check your local listings. Unforgotten Seasons 1 through 5 are available to stream on PBS Passport for members.