Initial Ideas

I've been thinking about some ideas for my own trailer and I think it'd be quite interesting to break the conventions of a typical thriller and give the audience something unexpected by having the female character as the villain and the male character as the victim yet set it up in to look like the female is in fact the victim but then at the end of the trailer show that she's the villain. I got the idea from watching some of a TV show on Channel 5 a few days ago called 'Women Who Kill' and thought that it would be worthwhile at least trying to include it in my own project.
Right now the vision of the trailer I have in my head is of a woman walking down dark alleys looking scared, checking all around her for anyone watching. She would be dressed quite innocently, be young and have blonde hair, a typical thriller victim. She could stand under a street light and make a call on her phone or look for something in her bag then walk off and the camera focuses on her feet. Later in the trailer the same feet would be shown going down some stairs to a cellar where she could unlock a very bland looking door, turn on some lights (strip lighting is what I imagine right now) and the camera cuts to the face of her victim - a young guy - who's tied up on the floor with gafa tape across his mouth looking terrified. Then it would cut to the girl again and the audience would realise she is in fact the villain.
If we couldn't have her going down stairs then an alternative idea is to have her going into a warehouse.