Abstract: A door lock mechanism is provided for positioning on the inside of the door and preventing the opening of the door. The mechanism comprises a main plate which slips over the doorknob handle, and a modified strike plate having an aperture structurally arranged for receiving a portion of the main plate. A simplified method is provided for easily and effectively securing a door, since the modified strike plate may be permanently secured to the doorjamb while the main plate may be quickly and easily positioned for locking the door. The method and apparatus of the present invention is well adapted for both commercial and residential use, since its components do not materially detract from the aesthetic qualities of the door.