“When I was in eighth grade my sister helped kill another girl.” That’s quite a first sentence. Our sister is Angel, and the girl she eventually helps to murder was Birdy. A and B. This is a schematic novel, one with interesting ways to explore shifting points of view. It’s got a nifty sense of place, too, and makes a fun pair with Ready, Set, Oh!, Diane Josefowicz’s fine and spooky 2022 novel.