Perhaps the red widow's human cover-identity is an aspiring actress or singer, who's now being menaced by a nascent greenhag in a similar profession. As the greenhag's Change comes over her, she spitefully murders younger performers whose beauty she herself is losing; at first, events would look just like a hag-hunt, with the red widow hidden in plain sight among the crowd of terrified young lovelies who fear they'll be next. Only near the end, after the hag has been exposed, would clues that there's a second feminine monster at work become evident, as the widow takes great pains to ensure that her own male victims' disappearances are likewise blamed on the hag.
If the PC party's not on the ball, they might kill the hag, miss the additional clues, and move on thinking they've saved the day, leaving the red widow alive and well ... and with a much-reduced field of competitors for potential star-struck suitors.
![Twisted Evil :twisted:](./images/smilies/icon_twisted.gif)