Hi I loved thissss. I didn’t even read the synopsis because I trust Alyssa Cole, and honestly I think it was really fun to go into it that way. But a quick rundown: a woman with dissociative identity disorder is hired as a caretaker for a castle on a private island, and to be paid, she has to survive the night. This book was giving Get Out meets And Then There Were None, with a lot of that mystery happening inside the MC’s head. This book felt like a BIG SWING and imo Cole pulled it off really well. 
Caveat: I don’t know anything about actual DID, but the book read like it was well researched.