Archie Mitchell was murdered in the Queen Vic on Christmas Day
Note: This story contains plot spoilers and reveals the identity of Archie Mitchell's killer.
EastEnders has revealed who murdered Archie Mitchell in a live episode marking the soap's 25th anniversary.
The BBC said even the actor playing the killer did not know until 30 minutes before the live transmission. Ten possible endings had been rehearsed.
The show went smoothly, apart from a couple of fluffed lines, and included the surprise death of a main character.
Bradley Branning, played by Charlie Clements, fell to his death off a building in Albert Square.
The revelation of Archie's killer marks the culmination of a long-running plotline that the BBC hopes will draw in millions of viewers.
Archie, who had amassed a string of enemies during his brief time on the show, was bludgeoned with a bust of Queen Victoria in the Albert Square pub on Christmas Day.
Den and Angie
Newlyweds Stacey and Bradley had been about to flee before the tragedy
At the end of Friday night's episode, the killer revealed herself.
Bradley's new bride Stacey (Lacey Turner) saw him fall to his death, and then admitted: "I did it. I killed Archie. It was me."
Tension had built throughout the programme with characters accusing each other of the murder.
Phil Mitchell (Steve McFadden) ransacked Ian Beale's house looking for evidence. Janine Butcher (Charlie Brooks) confronted Peggy Mitchell (Barbara Windsor).
And Archie's daughter Roxy (Rita Simons) accused her sister Ronnie (Samantha Womack), who revealed she was sexually abused by their father.
In one nostalgic scene, Ian Beale (Adam Woodyatt) and Dot Branning (June Brown) watched a video tape from 1985 featuring grainy footage of classic early characters like Den and Angie, and Arthur Fowler.
ALBERT SQUARE TRIVIA
The show began as a twice-weekly show in 1985
It moved to four episodes a week in 2001
Friday will mark the 3,952nd episode of the BBC One soap
The only remaining member of the original cast of EastEnders is Ian Beale, played by Adam Woodyatt. He was 16 when the show began
Albert Square is based on the real life design of Fassett Square in Hackney, east London
Executive producer Diederick Santer said there had been several clues to the killer's identity - one of them in the Christmas Day episode, one midway through the investigation and a final undisclosed pointer.
The live episode, which had been in the pipeline for nine months, featured 51 members of the cast, who had been rehearsing for three days.
The 30-minute show was a massive technical undertaking, with 36 camera operators, rather than the usual four, capturing more than 400 shots.