Unforgotten is back on our screens for a fourth season, with Cassie and Sunny working alongside each other once more on a new cold case investigation.
The latest season sees DCI Cassie Stewart (Nicola Walker) and DI Sunny Khan (Sanjeev Bhaskar) investigate an unsolved crime involving headless remains found in a London scrapyard - and worryingly, the suspects in the case were all once newly qualified coppers.
Director Andy Wilson previously revealed an exclusive Unforgotten episode three Easter egg to RadioTimes.com - and which relates to cast member Liz Baildon (Susan Lynch), one of the four Unforgotten suspects.
ITV's cold case detective drama airs weekly – and the full box set won't be up online until after the final episode airs, so there's no risk of accidentally finding out whodunnit.
The first season aired back in 2015, and since then the acclaimed series has grown even more in popularity since its arrival on Netflix.
Nicola Walker and Sanjeev Bhaskar lead the Unforgotten cast, reprising their roles as the two central detectives, whose personal lives are also a key part of the show.
Written by Chris Lang, the fourth season began in February 2021 and promises to raise some "difficult" and personal questions for the crime-solving duo, so we can expect plenty more of the show's trademark twists and turns.
Season four sees Cassie and the backpack-toting Sunny once again face a historic murder case and unearth long-buried secrets in pursuit of justice, with Cassie additionally grappling with personal problems at home.
The trailer was released back in February, and teased Cassie's apparent unravelling and anger at (potentially) multiple suspects in the case: "There is a small part of me that wants to punish them."
However, she could also be talking about wanting to punish the police force itself, which lets her down badly right at the start of season four, episode one.
At the start of the season we saw Cassie's petition to leave the force early and receive her full pension effectively denied. With her father's increasingly apparent health issues at the forefront of her mind, a bitter Cassie returned to her old stomping grounds, supported by Sunny.
Here's everything you need to know about Unforgotten season four.
When is Unforgotten on TV?
Unforgotten season four started on Monday 22nd February at 9pm on ITV. The series airs weekly on Mondays on ITV.
The show's official Twitter account has invited viewers to tweet out fan theories using the hashtag #UFTheory.
Filming for season four resumed in September 2020, following a hiatus due to the coronavirus pandemic and lockdown.
A tweet from the official Unforgotten account read: “We’re back! #Unforgotten will return to your screens in 2021 on @ITV!”
Sanjeev Bhaskar also posted on Twitter on 20th September 2020, including a picture of Sunny’s much-loved backpack alongside the caption: “Transformation complete. Let’s go to work.”
Series three finished in August 2018, but ITV only confirmed series four began filming the week of 14th January 2020. However, it had to be put on pause due to the pandemic.
In a recent interview, Chris Lang lamented the gap between filming seasons three and four, and the long production delay the pandemic caused.
"When Unforgotten three broadcast in the summer of 2018, and we were immediately asked to make series four, Nicola, Sanjeev and I, went out for lunch and all agreed that although we were delighted to be making another series, we needed a short break to recharge our batteries. Which is why we did not end up going into pre-production on series four till October 2019, to start filming in January 2020.
"Oh. If only we had known," he said, before adding: "When lockdown happened, we were eleven weeks in to shooting and just four weeks shy of completing principal photography. So near and yet so far - suddenly those four extra weeks I took off to learn macramé now seemed absurd. More absurd even than they seemed at the time."
When is the next episode of Unforgotten on TV?
Unforgotten season four usually airs Mondays at 9pm on ITV.
However, episode three didn't air Monday 8th March 2021 due to Meghan Markle and Prince Harry's Oprah interview showing in the drama's usual 9pm slot on ITV.
Unforgotten episode three aired on Tuesday 9th March 2021 at 9pm on ITV.
However, episodes four, five, and six are set to air in the usual weekly time slot at 9pm on Mondays.
How many episodes are in Unforgotten season 4?
There are six episodes in Unforgotten season four.
The six-part series means we're given plenty of time to get to know our four Unforgotten suspects, alongside Cassie and Sunny's respective home lives.
Unforgotten season 4 plot
Each series sees DCI Cassie Stuart and DI Sunny Khan take on a historic murder case after human remains are discovered, as they attempt to get to the bottom of a crime which has remained unsolved.
The new six-part run of episodes is written by Unforgotten creator Chris Lang and directed by Andy Wilson, who have teamed up for every series so far.
The fourth series kicks off with the discovery of Millwall Football Club supporter Matthew Walsh's dismembered body in a scrap metal yard, but the team believes it had previously been stored in a domestic freezer for 30 years.
Considering he had gone missing in the '90s and the owner of the freezer is dead, the mystery behind Walsh's death will be a hard one to unravel. Especially since Cassie has made the decision to retire from the police force for "her own sanity and wellbeing."
However, according to ITV, "Cassie faces an impossible dilemma when she learns she isn’t entitled to her full pension payment unless she completes her thirty years of service. Disappointed and angry with her superiors and the system, Cassie has to make the gut-wrenching decision to return to work."
Though her relationship with John is going strong, difficult times lie ahead with her son and her father, Martin, who suffers from early dementia.
Lang has also made it clear that we're not likely to see Cassie get a drug habit or Sunny swap his famous backpack for something a little more suave in series four, stating that he wants to stay away from typical detective tropes.
Speaking at the BFI and Radio Times Television Festival, he explained, "I think they’re often described as ordinary, and in a way I see it as a bit of a misnomer. They’re extraordinary in their ordinariness.
"Most TV detectives seem to often require external tropes to make them interesting. And to me they are external tropes – a fast car or a drink or drug habit or a mental health issue or some kind of quirk that seems a little bit bolted on.
"If you watch 24 Hours in Police Custody, they have none of that crap on, they’re extraordinary because of the job they do and how they inhabit the world which they live. I thought that was all you needed to show for it to be unusual."
Unforgotten season 4 cast
Both Nicola Walker and Sanjeev Bhaskar return to lead the Unforgotten cast.
As announced in January 2020, the cast for series four includes Sheila Hancock, Susan Lynch, Phaldut Sharma, Liz White, Andy Nyman, Clare Calbraith and Lucy Speed. (You can read our dedicated Unforgotten season 4 suspects breakdown here.)
Peter Egan returns as Cassie's dad, while Alastair Mackenzie plays John Bentley. Carolina Main returns as DC Fran Lingley, Lewis Reeves will be back as DC Jake Collier, and Jordan Long will play DS Murray Boulting.
Previous actors to take part in Unforgotten include Alex Jennings, Kevin McNally, Trevor Eve, Mark Bonnar, Gemma Jones, Tom Courtenay, James Fleet and Bryony Hannah...
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Unforgotten season 4 trailer
You can watch the ITV trailer for Unforgotten season four below.
What happened at the end of Unforgotten season 3?
**Spoiler warning: Do NOT read this unless you have seen the Unforgotten series 3 finale**
In a dramatic series finale, it emerged that Hayley Reid was part of a much larger and even darker story – and Dr Tim Finch (Alex Jennings) was a rapist, serial killer and psychopath. His respectability was all a façade. Once he realised the game was up and he would be going to jail, he let the mask slip and the man underneath was finally visible.
The only way for him to regain control of this situation was to tease the police with something they want: information.
As Lang told RadioTimes.com: “At that point, he thinks, ‘okay, well I’ve been kind of waiting for this moment all my life.’ He thinks, ‘I’ve had a good run.’ He’d been probably killing for 25, 30 years, and at that point he thought: ‘Okay, I’ve lost control of my liberty, but I do still have control of the information that I hold.’ He’s going to start spooning it out.”
As Dr Finch's revelations got to Cassie, she decided to take a little time away from her job to recover and to give romance a chance with DCI John Bentley (Alastair MacKenzie).
Chris Lowe (James Fleet) regained the trust of his fiancé and moved into their house together, while Pete Carr (Neil Morrissey) lost his wife and kids when his lies were exposed.
TV host James Hollis (Kevin McNally) also had to deal with a shattered marriage, although he was beginning to repair his relationship with the troubled grown-up son he had suspected of killing Hayley for all these years.