It's been over five months since Kat (Jessie Wallace) started cheating on husband Alfie once again, and three suspects still remain in the frame - Branning brothers Derek, Jack and Max.
With Alfie (Shane Richie) now at breaking point over Kat's lies, he has decided to follow her in a desperate search for answers - which leads him to the secret bedsit on George Street in tonight's episode.
When Alfie confronts Kat in a furious showdown, she initially refuses to be honest with him about her lover's identity - insisting that she hasn't slept with the guy in question since Alfie first found out about the affair in September. However, Alfie still wants to know the man's name - how will he react when he discovers the truth?
EastEnders airs tonight at 7.30pm on BBC One.
> Read our spoiler for tonight's 'EastEnders' episode
> Read more 'EastEnders' spoilers and news