From the introduction:
Welcome back to Bedlam! So, the original book just didn’t hold enough unpleasantness for you, eh? Well don’t worry, here’s all the stuff that didn’t fit. That should be more than enough vicious mayhem and hopeless bleak despair to suit even the most jaded enthusiast.
Before we get started, let’s go over what this volume contains and how to use it. "Straight Out of Bedlam" is a collection of supplementary material for Plain Brown Wrapper Games’ campaign setting "Bedlam City." None of it significantly changes anything in the main volume- we wouldn’t undercut your campaign like that. None of it contradicts anything in the main book, or sends any of its plot arcs skittering off in some new direction. Nor is any of this material necessary to run a perfectly satisfying game in Bedlam. Instead this is all supplemental/extra stuff to make your campaign come more vividly alive.
We’ll frequently make reference to "the Main Book" in these pages, and if we’re referring to something on a particular page of that volume, instead of this one, we’ll use this notation: (see Bedlam City, Page 23). However, while we intended this volume to be used as a companion piece to Bedlam City, adding to and enhancing it, there is no reason why you couldn’t adapt a lot of the material to some other campaign setting.