EastEnders fans were stunned last month when Billy Mitchell fell into the arms of Tina Carter after his daughter Janet was hospitalised.
Now their shocking indiscretion will come back to haunt them next week when Tina fears she may be pregnant.
She will confide in sister Shirley, who knows about the one night stand, when her period is late and she urges her to buy a pregnancy test.
When Tina, already a mother-of-one, goes to buy the test, she'll bump into none other than Billy and his wife Honey.
How will Billy react to the prospect of a love child?
Could this be the end of his marriage?
Passion between unlikely lovers Tina, played by Luisa Bradshaw-White, and Billy (Perry Fenwick) erupted over Halloween when she was involved in a hit and run.
Unbeknownst to Billy at the time, Tina was behind the wheel when his little girl was struck by a car and left on the roadside.
He turned to her for comfort after Honey threw him out of the hospital and her guilt led her to give him more than just a shoulder to cry on.
When Billy later discovered Tina was to blame for the accident, he didn't tell Honey or the police after Shirley threatened to expose his infidelity.
But how will he be able to hide the truth if Tina is pregnant?
The baby bombshell is another worry for the Carter clan in the run up to Christmas, as they already face being made homeless.
In jaw-dropping scenes aired last week, the family discovered they had been duped by Weyland and Co, who intend to evict them so they can demolish the Queen Vic and build new flats.
Could Tina find herself out on the streets with a new mouth to feed?
All will be revealed in the much-anticipated festive episodes, which EastEnders boss John Yorke has promised will be the soap's most dramatic Christmas yet.
"This Christmas is going to be a classic EastEnders Christmas – the time of year when EastEnders should be at its very best – and we can't wait for people to see it," he said.