Now, prior to encountering this book, I was unaware that Gahan Wilson was a writer. I was certainly familiar with his twisted illustrations for various well-known national magazines (among them The New Yorker and Playboy), so there was an immediate assumption that this book was likely to be long-form versions of the macabre humor he infuses his cartoons with. This was not far from the truth.
I must admit to feeling a bit awkward with discussing fiction, having steered clear of it for such a long period. Wilson has an interesting approach, however, which is not unlike the "window on a moment" that is a standard of his better known works. There are few tales here with much of any "context" or "backstory" provided; they start at a point and run forward with the strangeness and light horror building without getting into the details of how things came to be how they are within the telling. Most notable of this approach is a story of a fellow with a traveling "carnival" of sorts, but this carnival exists, as it turns out, simply to lure hoards of zombies to their destruction at every stop along the way. There's zero explanation of how the rural backroads of Kansas became so Zombie-infested (like, it would appear, pretty much everywhere else), just how the protagonist manages their enticement and elimination, before moving on to the next region.
In many of these stories, common items are simply not the way they are in the world outside the story, but exist in a world where they're the only thing amiss; among these: cats, birds, and assorted plants. There's even one in here that I wish somebody would option to make a twisted movie out of, a bizarre little tale called Hansel and Grettel, but which bears only the slightest similarity to the classic dark fairy tale.
Again, these stories exist in their own little bubbles of reality, and leave the reader with a whole raft of questions at the end of most, leaving no explanation of a multi-specied Mars, a fiction character who conquers both his author and his editor to achieve an existence beyond the pages of his book, and various forms of the ill-mannered dead.
This does seem to be out of print at the moment, yet seems to have a certain popularity, as the used versions of this paperback edition aren't particularly cheap. Your best bet is probably a used copy of the hardcover, which will set you back around $2.60 (plus shipping) for a "very good" copy. If this style of lucid, humorous, macabre writing appeals to you, I'm sure you wouldn't regret the read!