Sanctuary Asylum is a supplement for The Vigilante Hack.
The bulk of the book discusses the titular asylum. There's a description of the asylum which has a slight continuity error with A City Full of Sinners. The description says the asylum is near the city of Dreamsend, but according to A City Full of Sinners, Dreamsend is a neighborhood in Apollo City. This isn't a big deal and the books were written by different folks. The asylum was built in the 50's and is independent of all government support or aid. It is divided into five wards and each is unofficially ruled by a "Baron." Each of these barons gets a one page write-up (and have HD listed, like the villains of the core book). Interestingly enough, there isn't an actual floor plan for the asylum. However, there is a nice random table to help you generate it. This is followed by a quick asylum patient generator which is super useful. Drugs are often used in the treatment of mental health and this book includes some new ones. However, unlike the somewhat beneficial drugs of A City Full of Sinners, these "Psychochaotic Drugs" are meant to "induce sanity" and are full of nasty effects and have no benefits. The description of the asylum ends with two short adventures.
In addition to the asylum content, the book includes more material. There's a new class, the cat burglar, which is basically Catwoman. There are also 10 pregenerated characters with artwork (which is color in the pdf and black and white in the OBS print on demand version). While these are cool, especially the new class, they seem really out of place in a book about an asylum. It feels like they're just there for padding and because they didn't have another book to go in.
I know this review is a bit more negative than my previous reviews for The Vigilante Hack, but I still loved this book and really recommend it if you're running the game. You can get Sanctuary Asylum here.