Watch Her Disappear by Lisa Regan

Lying on the ground, the girl’s prom dress, the colour of champagne, shimmers in the dying light. A corsage of wilting pink sweetheart roses decorates her wrist. She is perfectly still, like a delicate china doll, trapped forever in a sleep from which she will never wake…
When a call comes in about a young girl found dead at a high school prom—her life drained away from a fatal stab wound—Detective Josie Quinn drops everything to attend the scene. Taking in the girl’s neatly braided hair, Josie feels a flicker of recognition. But no one comes forward to identify this innocent child, murdered on what should have been the happiest night of her life.
Trawling missing persons files, Josie realizes where she has seen the girl before. Gemma Farmer disappeared a few months ago, shattering her family. But why would her body appear now, on her sixteenth birthday? Josie’s only clue is the five neat little cuts on Gemma’s pale arm. Days later, another missing girl shows up, tucked neatly into her bed on the morning of her birthday, her favourite teddy beside her, her skin as cold as ice—and the autopsy reveals scars on her arm matching Gemma’s.
Her head spinning, Josie’s fears the marks are a serial killer’s twisted way of counting his victims. How many other innocent lives have already been lost, and how many more could follow? The case takes a terrifying turn when a local girl goes missing just days before she turns sixteen.

Clock ticking, Josie turns the town upside down in search of answers. But when her own chief comes forward with the missing piece of a devastating puzzle spanning decades, will it be enough to get inside the mind of the most unexpected and elusive killer she has ever encountered, or will another precious life be taken?