What's the Name of That Book??? discussion

I remember reading a book around the years 2015-2017. I can remember what the cover looks like but can not remember the title of the book or author. I can recall it was a YA thriller/mystery book. I know it had the word "letter(s)" in the title but every time I try and do a search, it never comes up. I do remember that the plot was about a group of friends being sent anonymous letters and told to go to a house. They all arrived and they were having a dinner party but then bad things started to happen (don't want to spoil so, I will be vague with that last part.) I only want to find the book because I want to re-read it and let my friend borrow it after talking with her about it. I have been trying to find it for the past couple of hours, I thought I owned the book but can not seem to find it with the rest of my books. When I did search up the plot, I got "Someone Is In Your House" but that isn't the book. As stated, I remember that the title had the word "letter(s)" in it and a number (I want to assume the number was 7 (seven).)

This sounds similar to This Lie Will Kill You by Chelsea Pitcher.

Franki, how old are the main characters? Is this book for adults? (YA = teens, in this group)

I added some details to the header/ topic title. Feel free to edit it.

Angela wrote: "This sounds similar to This Lie Will Kill You by Chelsea Pitcher."

YES!! THANKK YOU!! Now that I see the cover, that is the book!!! You are a life saver!

Kris wrote: "Franki, how old are the main characters? Is this book for adults? (YA = teens, in this group)

I added some details to the header/ topic title. Feel free to edit it."

Aaah thank you! I found the book thankfully!!