The plot of the movie isn’t clear. I’m guessing the goal is to rid the cats of the evil influence before they kill someone or get killed by someone who’s trying to defend themselves. But how is she going to achieve it?

Presuming that the character’s weakness is that she has social anxiety and is afraid of interacting with people because it will expose her as socially deficient, maybe the plot could be something that forces her to interact with people. So the only way to save the cats and their potential victims is by approaching strangers and talking to them.

Including a central antagonist could work. Maybe it’s a lonely middle aged man who is using the cats to murder seven of his friends who don’t talk to him any more and he feels abandoned.

What if it’s on New Years Eve? Lonely people feel even lonelier when everybody around them is busy partying and celebrating with other people. So the woman with social anxiety might have to hunt for the villain who derives power from being around people. As midnight grows nearer, maybe he moves to bigger and wilder parties, so the heroine will have to become even more uninhibited to get to him.

The exact ideas here aren’t prescriptive, but definitely think about how the character’s weakness is conflicting with the plot of the story.