SPOILER WARNING: Plot and ending details for Unforgotten Season 4 follow.

Unforgotten is a critically acclaimed British crime drama that has been on air since October 8, 2015. The series follows two detectives while they solve cold cases. 

DCI Cassie Stuart (Nicola Walker) and DI Sunny Khan (Sanjeev Bhaskar) lead a squad of London detectives to investigate disappearance and murder cases. To date, 24 episodes have been released, which are spread across four seasons. 

Each season focuses on a different case. It also features seemingly unrelated people who are eventually shown to have a connection to the victim.

The emotional consequences of the incident are also addressed in the lives of those affected as the murder case unfolds. For four seasons, Walker played an excellent role as DCI Stuart. Unfortunately, she is saying goodbye to the role forever. 

Is Nicola Walker Leaving ‘Unforgotten?'

Season 4 ended with a shocking twist. DCI Stuart finds herself in a terrible car accident, and as a result, she dies in the hospital. Since Walker's character is no more, she is leaving Unforgotten. 

However, the fate of DCI Stuart was pre-planned by Walker and the creator of the series, Chris Lang. In an interview with Radio Times on May 13, 2021, Lang mentioned that he and Walker discussed DCI Stuart's death while filming season three.

Therefore, with a mutual decision, they killed off Walker's character. Similarly, there was no debate about keeping the character alive for future seasons because they felt the actress leaving the show was right. 

Lang added that it would have been easier to write the story so that DCI Stuart would come back in the future. But he believed Walker would not like that. 

Hence, they made a bold decision to move into "a new iteration of the show." Of course, Walker was sad to leave the show and her beloved character, but it was what she wanted. 

However, she took a valuable souvenir from the show to remember her days in Unforgotten — DCI Stuart's badge. The badge hangs proudly in Walker's office.

I think that’s really all I took, but that was the most meaningful thing to me because it was around my neck the whole time. That’s what she was carrying around, this weight. It’s a really nice thing to have to remember her by.

While Walker carried the show on her back for four seasons, her exit does not mean the end of Unforgotten. 

The Future of 'Unforgotten'

Unforgotten was renewed for Season 5 on March 30, 2021. Bhasker will reprise his role as DI Khan, and he will be joined by a new detective. 

Lang stated that he had begun work on the new character who would take over for DCI Stuart. He also revealed that the unknown figure and DI Khan's new "partner in crime" will be a woman.

He has already written the plot and the character backstory of the upcoming season. He called his writing "an evolutionary process" since he will edit her story according to the show. 

Regardless, it is unknown who has been cast as Walker's replacement. The Season 5 of Unforgotten will premiere in 2022.