Mary Taylor will make a devastating discovery about the love of her life which threatens to ruin her relationship with Norris Cole for good.
The Coronation Street florist, played by Patti Clare, is keen to get a divorce from Norris in order to pursue a new romance with builder Jan.
Long-term friends Mary and Norris married in a bid to win a competition back in 2017.
But two years prior Mary was infatuated with Brendan Finch, played by Ted Robbins.
Ted had been the editor of supernatural magazine The Inexplicable and he and Mary began having an affair. But May was heartbroken to find out that he already had a wife.
Coronation Street teases another surprise return as Norris drops bombshell on Mary
His wife Bridget later discovered about Mary and slapped her, branding Mary a "scarlet woman". Mary is left even more devastated after Brendan accuses Mary of stalking him.
The ITV soap will return to the storyline in sad upcoming scenes.
Soap queen Sharon Marshall appeared on This Morning and revealed what viewers could expect: "The love of her life - do you remember Brendan came along? And he was married and he was a rotter but she proper fell for him.
"It will turn out that he had been writing her love letters and he'd left her an engagement ring and Norris never told her about it.
"So that was her chance of happiness..."
Poor Mary! How will she react when she discovers the truth?
*This Morning airs Mondays, Wednesdays and Fridays at 7.30pm and 8.30pm on ITV
