I don't want to send you into book club with made-up information, so I have to be straight with you: I'm not familiar with *Nineteen Quiet Rooms* by Ottilie Marsh. I can't find that book in my knowledge, and I'd rather not invent a twist that could leave you confidently discussing a plot that doesn't exist.

A few possibilities:

- **The title or author might be slightly off.** Do you remember any other details—what it's about, when it was published, where you heard about it? I might be able to help if I can figure out the actual book.
- **It could be very new, self-published, or obscure.** In that case I genuinely don't know the ending.

If you want to salvage things before tomorrow:

1. **Skim the last chapter or two** — even 20–30 minutes with the ending is often enough to contribute to the twist discussion.
2. **Check Goodreads or StoryGraph** for reader reviews, which often discuss the ending (sometimes with spoiler warnings).
3. **Search "[title] ending explained"** — someone has usually written a breakdown if the book has a notable twist.

If you can tell me more about the book (genre, what you read so far, character names), I'm happy to help you piece together what's going on or prep some talking points for the meeting.