Cord Revolver

BACK TO BATMAN

Staring down through the broken glass.  Listening.  He pulls a tiny
revolver from his belt.  A barbed metal dart sticks out of the barrel.
Batman aims it through the hole, fires.

ANGLE ON MUSEUM RAFTERS

The dart embeds itself deeply into a rafter.  Attached to it is a white
nylon cord.

BACK TO BATMAN

Securing the other end of the cord.  He hooks himself to it with a
clip, glides through the opening in the glass.

BACK TO RAFTERS

Batman shoots silently along the cord to a rafter, lands gracefully,
looks down.