The Shadow Sister - by Lily Meade

"Sutton going missing is the worst thing to happen to Casey, to their family. She’s trying to help find her sister, but Casey is furious. And she can’t tell anyone about their argument before Sutton disappeared. Everyone paints a picture of Sutton’s perfection: the popular cheerleader with an entourage of friends, a doting boyfriend, and a limitless future. But Sutton manipulated everyone around her, even stole an heirloom bracelet from Casey. People don’t look for missing Black girls—or half-Black girls—without believing there is an angel to be saved.
When Sutton reappears, Casey knows she should be relieved. Except Sutton isn’t the same. She remembers nothing about while she was gone—or anything from her old life, including how she made Casey miserable. There’s something unsettling about the way she wants to spend time with Casey, the way she hums and watches her goldfish swim for hours.
What happened to Sutton? The more Casey starts uncovering her sister’s secrets, the more questions she has. Did she really know her sister? Why is no one talking about the other girls who have gone missing in their area? And what will it take to uncover the truth?"