After months of speculation, the identity of Kat's secret lover will finally be exposed in what is set to be an explosive instalment of EastEnders.
Fans will see the wayward bar lady, who has been cheating on her husband Alfie for months, finally get caught in a dramatic showdown. Her web of deceit will unravel in scenes set to play out tonight at 7.30pm on BBC1.
But while the bombshell will rock the Moons' marriage, the repercussions of Kat's affair will continue in episodes running into the New Year.
By the looks of the official trailer, despite Kat begging him not to dump her, an angry Alfie decides not to forgive her infidelity and will be seen throwing his wife out of the Queen Vic.
The three Branning brothers - Derek, Jack and Max - are all still suspected of cuckolding Alfie by sleeping with Kat. But which one is it?
Either way the truth could potentially cause a lot of heartache for everyone involved as Max is preparing to marry his wife Tanya for a second time and Jack is dating Sharon.
Earlier this month, Shane Richie, who plays Alfie, revealed that fans are in for a surprise.
"It's really interesting about how we play the Branning card as to which one of them it is," he told the Radio Times.
"The way it's worded, you believe it's one brother in particular and then that all changes and you go, 'Oh, it's him!' Because we make people believe it's another Branning - the way it's worded, the way I face up to one of them.
He added: "The audience will all think it's one person in particular, but then I throw a curve ball and it all kicks off. It's great."