It's not just fans who'll be kept guessing about Archie Mitchell's killer on EastEnders - the actors won't be told until the last minute either.
Scriptwriters have written 10 possible endings to the big live show on Friday - and all of them are being rehearsed.
The actor who is the real killer will be given a nudge about 30 minutes before the live show starts.
Among the suspects are Peggy Mitchell, Janine Butcher, Ian Beale and Bradley Branning.
The show will go out live for the first time ever to mark the 25th anniversary of the soap.
The writers have kept the killer's real identity a secret until the last possible minute to make sure no-one leaks it to the press.