Until today, cast members were in the dark over whether they would be appearing - or even speaking - in the episode.
The script, written by series consultant and lead show writer Simon Ashdown, was delivered to the cast ahead of the first read-through on Monday.
Producers, however, have held back the most important page - the 'Who Killed Archie?' reveal scene. The killer's identity will remain under lock and key until the night of the live episode and the actor playing the culprit will reportedly be informed of their character's sin halfway through the broadcast.
An EastEnders source told DS: "Producers wanted to make sure the script was perfect before sending it out. It's been the talk of the studio for the last three weeks - nobody knew a thing until today."
They added: "Still only seven people know the killer's identity - and that's the way it'll stay until the night."
EastEnders' live silver anniversary episode will be broadcast on Friday, February 19 at 8pm.
> Click here to read more about EastEnders' 25th anniversary