With Kat's mystery lover soon to be revealed and Derek tipped to let the Brannings know what Max has been hiding, the preview video promises that "secrets aren't safe" and "time is running out".
Unseen snippets from the big episodes show Kat begging Alfie not to dump her after he breaks down the door to her secret lover's bedsit, at breaking point over his wife's lies.
The Branning family are also seen in the build-up to Max and Tanya's Christmas wedding.
Watch the trailer below:
EastEnders airs an hour-long episode on Christmas Day at 8.45pm on BBC One.