Peter Barlow will discover that Billy Mayhew was responsible for his twin sister's death, in a dark Corrie twist this Christmas.
At the moment Peter's completely oblivious about Billy's part in the car crash that killed Susan Barlow - who was Adam's mum and Peter's twin.
But this Christmas the whole dark story is revealed - in a way that's first surprising and then very dark.
Billy's secrets all start to unravel when he has to go to court to face charges for punching Peter a couple of months ago.
Peter speaks up for the vicar, saying he doesn't deserve to go to prison. And for a few minutes, things look to be resolved.
But outside the court a fight breaks out - not between Peter and Billy, but between two strangers. But the two Corrie residents get involved, trying to break things up.
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Billy's shoved over and falls to the ground during the fight, but he seems okay - at first - and the pair get back in the car to head home.
I don't think I've ever gone this far with Peter before. I don't think he knows what he's doing.
It's not long before the vicar's in a lot of pain, though. Turns out, a metal lucky charm that Summer gave him has got itself embedded in his leg and poor Billy's bleeding heavily.
Terrified, Peter stops the car and tries to stop the bleeding, while he calls an ambulance.
But Billy's sure he's dying and makes a confession to Peter, telling him he deserves death because he killed Susan!
So how will Peter react to the shocking news? Not well, is the answer.
"Peter takes his hand off the wound and watches him start to die, but then comes to his senses and puts his hand back on again," Chris Gascoyne, who plays Peter, told Digital Spy.
"It's just shock for Peter. He can't take in what he's told him. Then later he starts to formulate some sort of mad, misguided revenge plan."
And what a revenge plan it is! Peter makes Billy drink two bottles of vodka and then he locks him in the boot of his car!
"It's very dark," said Chris. "It's probably the darkest part of the character.
"I don't think I've ever gone this far with Peter before. I don't think he knows what he's doing."
The chilling story will spill over into Christmas week and have repercussions into the new year, too.