Alfie Moon will be left exposed as the truth about his past with Hayley Slater comes to light, and there will be blood on the hands of someone in Albert Square.
The seasonal special of EastEnders, to be aired on Christmas Day, will feature violent acts and revelations.
Mick Carter and his wife Linda remain tense as a chill descends on the Queen Vic despite the festive cheer, and emotions run high for the Slaters.
Producers of the popular BBC soap have promised that, by the end of the special episode, blood will be spilled in Walford.
Christmas Day is filled with paranoia for Alfie (Shane Richie) after his relationship with Hayley (Katie Jarvis) sees a further transgression under Kat Slater’s roof, leading the unconventional household to question who knows what as the truth bubbles to the surface.
EastEnders producer John Yorke said the Christmas episode will contain something “sinister and dark”.
He added: “Kat (Jessie Wallace) is finally coming to trust Alfie, arguably foolishly. Alfie is doing anything he can to keep the secret.
“What’s clear is that someone at the end of Christmas is going to have a lot of blood on their hands.”
Mick (Danny Dyer) and Linda (Kellie Bright) will face personal battles in the pub in between serving drinks, in the wake of a climactic confrontation.
Max Branning (Jake Wood) is seen in moments of tenderness on the Square as Stacey Slater (Lacey Turner) seeks help in the confusion of Christmas.
There is further drama to follow as the show enters the new year, with producers promising that 2019 will be a “big year for the Slaters”.