Stacey Branning (Lacey Turner) has been desperately struggling with postpartum psychosis since the birth of her baby son, Arthur.
Show bosses have now revealed that her psychosis is set to intensify further, to coincide with the BBC’s In The Mind week, which will focus on mental health awareness.
And it’s set to have huge consequences for her boyfriend, Martin (James Bye).
In the episodes of the week beginning Monday February 15, the BBC says: "Stacey's story intensifies and viewers will see her make a life-changing decision that hugely concerns Martin."
As viewers are well aware, Martin is of the belief that he is the biological father of little Arthur, and has been caring for him since Stacey was sectioned under the Mental Health Act.
However the tiny tot is, in fact, the son of Martin’s best friend, Kush (Davood Ghadami)… something which Martin has yet to discover.
Could Stacey’s decision involve telling Martin the truth about her baby boy?
Or could she be set to make a big decision about their relationship? After all, Martin was keen to marry Stacey just a few months ago - something which she turned down at the time.
Perhaps his behaviour throughout her mental health ordeal has changed her mind?
If so, we hope that Martin will find it in his heart to forgive Stacey and Kush for their betrayal.
Teasing the big reveal, James Bye said to Inside Soap: "I think it's going to be an implode or explode situation.
“He'll either jump off a bridge or go crazy with Kush and Stacey.
“If it was me, I wouldn't be able to get my head around it. I've got kids myself so it's not something I ever want to think about!”
James added: “I am keen for him to find out, but at the moment I don't think it can happen, what with everything that is going on with Stacey.
"While I don't want it to end up being a long, drawn-out storyline, the upcoming scripts are really strong."
Actress Lacey Turner and the soap's executive producer, Dominic Treadwell-Collins, will appear on BBC One's The One Show on Monday February 15th to discuss the storyline and their research.
Speaking in December about the postpartum psychosis storyline, Dominic said: "We have always had a big commitment to Stacey's story and this time we want to explore the effects of postpartum psychosis on those with bipolar - something which, although a rare illness, is unfortunately more common when mothers with bipolar give birth."
Mind’s senior media adviser Jenni Regan told HuffPost UK: “We have been impressed by the dedication ‘EastEnders’ have shown in portraying postpartum psychosis sensitively.
“One of the main aims of our input into this storyline was to ensure that we challenge the myths surrounding this illness.
"We also advised the programme to adopt a realistic timetable to ensure that Stacey does not become unwell and then recover in the space of a week."
EastEnders will air these scenes next week on BBC One.