The Guest List was a fan favorite in 2020 with a lot of high recommendations. However, I believe that's thanks to marketing and not the story itself. This whodunnit is a bit lackluster, and will leave many readers feeling shorted.
The Island is isolationist horror at it's finest. Think "The Troop" meets "Knives Out". Characters are dropping like flies and it may not be until the very end that we know who is responsible.
Imagine a non-magical Dolores Umbridge. . . She lives in a small town, where she's burned every bridge. Who can the lone detective even rule out? Oh did I mention that detective is her nephew...