Since Christmas, viewers have seen sinister Silas Blissett (Jeff Rawle) prove a dangerous presence in the village - murdering innocent student India Longford and con artist Rebecca Massey.
Silas has also terrorised Lynsey Nolan (Karen Hassan) as she suspects he is the killer, but Waugh's character Cheryl Brady has refused to stand by her friend as she makes her allegations.
Waugh told PA of the plot's future: "All we know, to avoid leaks, is that he will strike again - someone is going and none of us know who it might be.
"We won't know because we're only being handed scripts as and when they come out, which is brilliant because it's keeping us all in suspense but it's really terrifying."
She continued: "So it could be me, it could be Lynsey, it could be any of the girls that he's been torturing."
Silas will be one of the characters to feature in the new series of late-night spinoff Hollyoaks Later, which returns to E4 on September 5.
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Watch a recent Silas and Lynsey scene in the video below: