Crank Lever

Filing Room (Water Treatment Plant 1F): shelves on the north side, next to the Control Room.

Fit it into the Control Room control panel: it restores power to the plant.

When you try to fit it, The Girl bursts in and throws Grace against the window. Shoot her with the Requiem (1 round stuns her on Casual and Standard, 2 on Insanity; a good spot for Bring Out the Big Guns) and run to the panel. To open the roof hatch later, restart the 3 power distribution units in the lower area (Roof Hatch Manual file).