Lucy Beale’s killer will be unmasked live on air during a special week of EastEnders episodes to mark the soap’s 30th anniversary.
Show bosses will be keeping the murderer’s identity a secret from cast and crew until just before the unveiling in February.
The anniversary of the BBC soap will include one 30-minute live episode and “live elements” in the other episodes.
BBC One controller Charlotte Moore said: “BBC One will bring the nation together to celebrate 30 years of EastEnders by going live across the anniversary week. Next February will mark a massive event on the channel by creating the ultimate ‘doof doof’ and finally reveal who killed Lucy Beale.”
Viewers have watched as suspicion has fallen on several different characters since Lucy’s (Hetti Bywater) murder in April, with the identity of the killer still a mystery.
The long-running soap marked its 25th anniversary in 2009 with its first ever live episode when it was revealed Stacey Branning (Lacey Turner) had murdered Archie Mitchell (Larry Lamb).
The live week starts on Monday February 16, 2015.