It's part of the show's 30th anniversary week, so two good reasons for a party.
Here are some tips on how to throw the perfect bash...
It may be a poor substitute for Albert Square, but choose a character to dress up as and pop down the local market to pick your outfit.
Will it be Whitney, will it be Max, will it be Ian?
Whoever you pick, gold hoop earnings, plastic leather jackets, fake fur and tracksuits could be on the shopping list.
You won't go far wrong with a chef's apron either.
Fill your basket with cheap crisps, sweets and drinks.
You may not be on first name terms with the cashier, or get into a row while you're in there, but if you try really hard you may just believe you're in the Minute Mart.
For the main course, it's just got to be fish and chips.
In honour of the Beale family, make it plaice.
Make your guests really feel like they're stepping into Albert Square.
A street sign on the front door, framed pictures of the cast around the room and the EastEnders theme tune on a loop would certainly help set the mood.
If you really want to push the boat out, why not create your own Queen Vic, complete with a bar, a royal sculpture and a licence above the door?
No Who Killed Lucy Beale party would be complete without some sort of competition to guess who the culprit actually is.
Whoever gets the killer right, gets the prize. Yay!
Sure, this may just be a bit of fun but at the heart of all this is the loss of a young woman's life (sort of).
Yes, she had a history of causing trouble and getting up people's noses, but do take a minute to remember Lucy Beale.
RIP Lucy, never forgotten.
We are in no way condoning physical violence, but come on, no EastEnders event would be complete without a bit of a verbal bust up.
After the big reveal, just let all that vent up frustration out of your system.
Frowning all night and generally being a bit glum could also help you get in the mood.
Have fun!
In true EastEnders style, after the party, head to a trendy club around the corner.
Ideally, you'll know practically everyone in there and the music will be so quiet you'll hear what the bloke at the end of the bar is saying.
You'll probably get into a row with whoever's serving the drinks as well.
Now you're really getting into the spirit of it.
If you're nursing a sore head the next morning after all that "loud music", get down to your local greasy spoon for a fry up.
And hopefully it will stop you feeling like this...
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Viewers have been guessing who did it for the last year, but on Thursday EastEnders will FINALLY reveal who killed Lucy Beale.