'Coronation Street's Ken Barlow will catch his future daughter-in-law Leanne Battersby cheating on his son Peter - with her ex husband Nick Tilsey.
The businesswoman, who is played by Jane Danson, rekindles her romance with ex-husband Nick (Ben Price) when he hires her to run his wine bar The Joinery but their secret relationship is cut short when Ken (Bill Roache) sees them together and threatens to tell the bookmaker (Chris Gascoyne).
A source said: "Leanne is wracked with guilt over the affair. She loves Peter, she loves his son Simon and they've been through a lot together - but Nick was her first love and she never got over that."
Nick and Leanne eloped to get married in Scotland in 1998, but their brief marriage was turbulent as they dealt with an abortion and the disapproval of the businessman's mother Gail Platt (Helen Worth).
Leanne is now set to marry Peter after proposing to him in the Rovers Return pub.
But her future husband is hardly perfect after he had an affair earlier this year and even committed bigamy when he last got married.
He married ex-Rovers Return landlady Shelley Unwin even though he was already wed to Lucy Richards.
The source added to The Sun newspaper: "Ken knows Peter is no angel, but blood is thicker than water and his loyalty is to Peter.
"He's worried for his son and for little Simon.
"Leanne regrets her affair with Nick, but there is a chance if Ken doesn't blab, Nick will."