Downton Abbey is set to go up in smoke in the first episode of series five, when a heartbroken Lady Edith Crawley accidentally sets fire to her bedroom.
Lady Edith, played by Laura Carmichael, is in bed weeping over her secret daughter, who she had to give up when her lover, Michael Gregson, mysteriously disappeared, but a book too close to the fireplace goes up in flames, putting the rest of the house and its inhabitants in danger.
Fans will see the family and servants scramble to get out in time and to save Downton, uncovering some house secrets along the way.
Executive producer Liz Trubridge said of putting together the stunt: "Because it was a stately home we couldn't set fire to it. The owners didn't want smoke damage to their house."
She explained that they had built a replica bedroom to burn at Ealing Studios, where Allen Leech's character Tom Branson hosed down the flames: "At the very end the cameramen got themselves in complete waterproof gear and were hosed down by Allen."
The series opener also sees the cast in 1924 having mixed reactions to the news that they have a Labour prime minister - some of the servants welcome the change, while butler Carson (Jim Carter) and members of the family including Hugh Bonneville's Earl of Grantham worry that their world is about to change, especially when the villagers ask Carson to chair a committee over the Earl.
Allen said that former chauffeur Tom, who now lives as part of the family with his daughter Sybbie after his marriage to the late Lady Sybil, would sympathise with those feeling the class system should be upset but would be unlikely to play a very active part in it.
He said: "It would be impossible for him to go back to the man he was. I think he's not as naive as he was when he arrived last year, but he's still very strong in his views."
Viewers will also see Anna (Joanne Froggatt) and John (Brendan Coyle) Bates struggling with whether to have a child. Asked if Anna's reluctance was due to worries that Bates was responsible for the death of Mr Green, after Lord Gillingham's valet raped her last season, Joanne said that wasn't the case.
She said: "I don't think Anna thinks for a moment that Bates is a serial killer. What I'd like to see for Anna and Bates as a viewer is different from what I'd like as an actor, because you like to play the drama, but it's important to have the happy times in between. They get moments of happiness and positivity for them, but it's not an easy journey."
Executive producer Gareth Neame promised more moments as shocking as the rape scene to come in series five: "We always try to have each season right angle moments you don't expect to happen, so I'd like to think so."
He added: "We hope to be back again next year. We think one year to the next so we'll see."