A security shutter having two units. Each unit has two panels hingedly connected to one another with one panel permanently affixed to a structure near one side of an opening. When closed, the panels of each unit cover the opening, and a securing mechanism is used to secure their positions. Further, each panel includes a plurality of spaced apart slats aligned in an alternating pattern relative to the plurality of slats on the adjacent panel such that, when the shutter is not in use and one panel overlays the other against the structure, the shutter unit appears as a traditional panel without spacing between slats.