EastEnders detective Emma Summerhayes (Anna Acton) may have been dropped from the investigation into Lucy Beale's murder, but that doesn't mean she's any less interested in identifying her killer.
And, as we saw in last week's official trailer for the BBC soap, Emma is about to make a huge breakthrough.
Picking up a phone, she furiously whispers to the person on the other end of the call: "I know you killed Lucy."
Now more details have emerged about the lead-up to that explosive moment, which comes just after a very dramatic Christmas episode.
Desperate to do something festive - and put herself in a position where she can finally ask some serious questions about Lucy's death - Emma arranges drinks for the Beales and the Brannings at the Queen Vic.
But things don't go to plan when the disgraced detective attempts to 'innocently' ask questions about the murder - and she quickly grows suspicious of the people around her.
Emma heads home alone and tries to put the pieces of the puzzle together - including a video which shows footage of Good Friday, the night of Lucy's death.
And, all of a sudden, everything falls into place.
That's right; Emma knows who killed Lucy, but what will she do about her momentous discovery?
And, more importantly, how will the person on the other end of the phone react to the news that their crime has finally been solved?
One thing's for sure, we wouldn't want to be in Emma's shoes if the killer decides to strike again…
WATCH THE TRAILER FOR YOURSELF BELOW:
EastEnders airs these scenes on Tuesday, December 30 at 7.30pm on BBC One.