The Silent Girls by Dylan Young is the first book in the Anna Gwynne series. What a great start!
17-year-old Nia has a sleepover in her family’s stable for her birthday one evening. Her father goes to check on her and finds her friend drugged and barely conscious and his daughter missing.
Soon, Nia is found dead, in a shallow grave, with her arm reaching out and stab wounds all over her body. Strikingly similar to Emily’s body found eighteen years earlier.