In scenes due to air in the coming weeks, Amy Wyatt (Natalie Ann Jamieson) and her mother Kerry (Laura Norton) will inadvertently start a devastating fire in which one person loses their life.
-> Leeds council officer warns against increasing Emmerdale coach tour numbersThe highly-teased plot will see Amy in debt to an ex-boyfriend from her past life in Belfast.
The day after Bernice Blackstock's Wild West charity fundraiser, Amy and Kerry will plot to steal the money raised to pay off Amy's debt.
However, after the pair take the cash, they discover they have been caught on CCTV and Amy decides they need to cover their tracks.
They let themselves back into the factory and sabotage the camera system before making their escape.
But in doing so they start a fire which rips through the factory.
-> Charlotte Armitage: Why we must praise work of BBC and Emmerdale in placing disabled people in spotlightAnd Tracy Metcalfe (Amy Walsh) will find herself trapped in the building's storeroom as the blaze spreads.
Norton, 36, said there will be "huge consequences" to their character's actions.
She said: "It's huge consequences because it was a tragic accident if anything like that were to happen.
"And at the end of the day they think that they just started a fire, and they knew it could be bad.
"But, yes, it's huge for any character, no matter how tough-skinned anyone is or however much trouble anyone's been in before, it's awful to think that you could be responsible for that."
-> ‘Why I am very different to my Emmerdale character,’ says Gaynor FayeShe added that filming for the pivotal fire scene saw shrapnel fly through the air.
She said: "It was brilliant. We had to stand back for the first one, they just sort of moved just out of the vicinity because it was too hot and there was shrapnel going everywhere.
"We got to view it and see the rehearsal, which was amazing. And we did the scene separately from the explosion as we were sort of set back from everybody.
"We were all genuinely emotional but excited at the same time."
Emmerdale continues on ITV.