I have to be honest with you — I can't find any record of a book called *Nineteen Quiet Rooms* by Ottilie Marsh. This doesn't appear to be a real published novel that I'm aware of, and I don't want to invent a fake spoiler summary that would leave you looking silly at your own book club.

A few possibilities:

1. **Title or author mix-up** — could it be something similar? Titles with "rooms" (like *The Quiet Tenant* or *Room*) or authors like Ottessa Moshfegh might be getting blended together?
2. **A very recent or obscure release** — if it came out very recently, I may not have information about it.
3. **A self-published or small-press book** — these often don't show up in my knowledge.

**For your book club situation:** A quick search (Goodreads, the publisher's site, or spoiler-filled reviews on StoryGraph) should get you a plot summary fast. Review blogs often have "ending explained" posts for twisty books.

If you can tell me anything else about it — the genre, what the story's about, or where your book club found it — I'm happy to help you piece together enough to participate tomorrow, or suggest talking points that don't require knowing the ending.