Now convinced that her fiancé Phil Mitchell killed Heather, a furious Shirley (Linda Henry) continues presenting her theory to Ben - still oblivious to the fact that the twisted teen is the real culprit.
As Shirley rants at Ben, she declares that Phil is a "lying, murdering piece of filth" - before furiously throwing a champagne glass across the room.
Ben (Joshua Pascoe) is petrified over the escalating situation and desperately defends his dad, insisting that Shirley has got it all wrong.
However, Ben's protests that Phil is innocent soon backfire badly as he accidentally lets slip a vital piece of information that only the killer could know.
The moment that fans have been waiting for has finally arrived as Shirley suddenly realises that Ben killed Heather. But what will she do about it?
EastEnders airs tonight at 7.30pm on BBC One.
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