Side Character; in a Supernatural Novel

"Young boys and girls travel to an isolated mansion after being promised a night of heavy partying in an isolated mansion with nobody to disturb them,

But as soon as they arrive, strange occurrences disturb the festive atmosphere, and the party turns into a genuine nightmare.

With their doors are out of the commission panic breaks out. Trapped in the mansion, they will have to stay together to get out alive, instead of the fun they hoped for, they meet an entity out to reap vengeance on them."

Dolores however finds out that this is the summary of the book she is in!

With her death written on the second page of the book, Dolores clenched her fists and promised to not be the deceased side character!