She is a chainsaw using serial killer responsible for a series of murders. Early on in the film the killer is shown fully clothed with their face covered, so their identity is a mystery, as is the fact it is actually a woman responsible.
Grace is first seen working as a waitress at a local egyptian themed restuarant. The movie's heroine thinks Grace is to be another victim of the killer and tries to save her, only for it to be revealed that Grace herself is the killer.
Grace captures the heroine and tortures her kidnapped father in front of her and tells her henchman to rape her. Some of the movie's heroes arrive in time and save their friend before she is raped. During a scuffle Grace grabs the heroine and takes her outside where they have a fight, which Grace eventually wins by knocking the heroine out with an object.
She then hangs the heroine by the neck between a giant crusher, and places her foot on the button that prevents it from crushing. If she removes her foot from it then the heroine would be crushed. One of the cop heroes arrives outside and shoots at Grace which doesn't kill her but causes her to release her foot, starting the crusher. The heroine pulls Grace inside the crusher with her and they fight briefly before the heroine climbs to safety and Grace ends up being crushed to death.