Blond preteen Olive travels to Mexico with her adopted Latinx siblings Charlotte and Darwin, to spend the summer at their Grandmother Lupé’s (possibly haunted?) hotel. They discover a series of strange artifacts which allow them to visit alternate worlds, and also a history of missing family members. All of this plot is wrapped up quite quickly, though the ending also leaves the door open for a sequel. I liked a lot of the concepts in this book, but it just didn't quite come together for me.