(This sounds like fun!)
I pound at the door and call for help, and also look around to see if there are any windows.
You call from help for a couple of minutes, until your our eyes stop on an old movie poster on the bulletin board:
Alien. In space, no one can hear you scream.
The irony is stunning.
The pub has windows, but they're protected by finely crafted wrought-iron window grilles. They seem to be very sturdy, although they can definitely be forced open with some power tool.