Plz help me find this horror film

I only remember the ending of the movie.
A policewoman(I guess) was bound by a man(the villain) in an abandoned building and a gun was attached next to her head; if she moved her feet, the rope would pull the trigger and the gun would be fired.
The man poured oil on the floor and set the building on fire, and he went out of the building.
The woman hesitated whether to kill herself by moving her feet and being shot in the head or to be burnt alive.
As the man walked out of the building, a gunshot was heard from behind, implying the woman had decided to shoot herself, and the man smiled and kept walking to a truck parked nearby. The movie ends like this.