Coronation Street will have a standalone episode focusing on Carla Connor's mental health in 2019.
Alison King's soap character will begin to crumble next year after the roof of the Underworld collapses and kills another cobbles regular.
New boss Iain MacLeod told Radio Times website: "This will trigger a massive story for Carla because it impacts massively on her mental health.
"She feels correctly that everybody is out to get her and she spirals off into a slightly delusional state.
"We’re doing something a little bit stylised, like the Ashley story I did at Emmerdale, but it won’t be quite as extreme as that.
"It’s a standalone episode that will be both mental heath focused and Carla focused. It will also be the reveal to the audience of who is behind the factory roof collapsing.
She spirals off into a slightly delusional state
"I’d hesitate to put a diagnosis on what it is affecting Carla, but the factory collapse has lots of unexpected offshoots into areas that give our amazing cast a chance to show off their acting chops."
The producer also explained he hasn't decided the specifics of the episode yet because he doesn't want to deviate too far from the overall feel of Corrie.
He explained: "We’re inside Carla’s head, but I’m still unsure about how far we explore what’s real and what’s not real.
"Other soaps have gone right off the deep end of that to very good effect, but Corrie is a different beast and I think you mess with the parameters of Corrie’s genre to your peril. We’ll be careful with it.
"The touchstone for me was Gary Windass’ PTSD meltdown around the time of the tram crash. It was more exaggerated things that were happening rather than hallucinatory."
Scenes showing the deadly factory collapse are expected to air in March.
Sean Tully, Izzy Armstrong, Sinead Barlow, Beth Sutherland, Kirk Sutherland and Gina Seddon are all tipped to be in the running to be killed off by the accident.
However, it is soon discovered the disaster was caused by "some sort of criminal enterprise".
"It’s a massive whodunnit which turns people against each other, and fractures the community," producer Iain promised.
He added: "It'll be every bit as intriguing. We'll start with the crime and then gradually reveal the motives afterwards."
- Coronation Street airs on Mondays, Wednesdays and Fridays at 7.30pm and 8.30pm on ITV
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