Show bosses recently released a summer preview video which sees Kylie (Paula Lane) uncover Marc's secret when she spots him dressed up as alter ego Marcia.
It has now emerged that Kylie decides to use the situation to her advantage as she makes her discovery shortly after being sacked by Audrey (Sue Nicholls) for causing chaos at the salon.
After recording video footage of Marcia on her phone, Kylie threatens Audrey by warning that she will reveal Marc's secret unless she gets her job back, according to the Daily Star.
It is thought that Marc's shock decision then causes fresh problems for his relationship with Audrey, who gets cold feet over their future.
Audrey reportedly tells him: "I'm not sure I can carry on like this. Like it or not, people round here will see you as a freak."
Coronation Street's new storyline for Kylie, Audrey and Marc is expected to air later this month.
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> Read more Coronation Street spoilers and news
Watch Coronation Street's summer preview video below: