She finds a book at her sister’s house and reads from it, this causes the Evil Queen of Darkness to be summoned. The Evil Queen possesses Susan’s beautiful body and uses her to seduce and murder men so she can sustain herself with their blood.
Susan dresses in her skimpiest clothing and hits the town looking for victims. Throughout the movie, she kills many men; by stabbing them in the head with a kick from her high heels, piercing them with hooks, cutting them up with a buzzsaw, shooting them with a gun and by using telekinesis to project sharp objects at them. After killing the men, Susan returns to the mirror where the Evil Queen resides, she feeds the Queen with blood through the mirror and helps her become stronger.
At the end of the movie Susan is commanded to kill her sister, she stalks her sister and shoots some sort of lightning at her. A man comes to try and save the day and shoots at Susan, but under the control of the Evil Queen she is invincible to bullets. Eventually another man called Beko frees Susan from her possessed state by using some kind of magic. He then manages to keep the Queen trapped within the mirror and seemingly kills her too, as she is last seen shattering into pieces as if she was made of glass.