The Vanishing Girl — Josephine Ruby

It's the classic girl detectives like you've never seen them before! Daphne Blake and Velma Dinkley have a terrifying new mystery to solve - and this time, the culprit is far more frightening than any man in a mask...
Popular Daphne Blake and über-nerd Velma Dinkley are not friends. They aren't enemies either, but they don't have any reason to speak to each other, and that's how they prefer it. The two girls grew up together - they'd been best friends since pre-K - but when they hit middle school, Daphne dropped Velma and never looked back.

These days, Daphne's deep in the popular crowd, daughter of the richest family in town, while Velma's an outsider, hiding from the world behind her thick glasses. When they run into each other in the halls of Crystal Cove High, they look the other way.

But then Daphne's best friend, Marcy - who happens to be Velma's cousin - goes missing. A century ago, there was a wave of disappearances in Crystal Cove, and many local people believe that supernatural forces were behind it. Now the whole town believes those same forces are back . . . and up to no good.

Daphne and Velma may be the only ones who can solve the mystery and save Marcy-if they can trust each other enough to try. Especially since the truth might be stranger-and scarier-than either girl can imagine . . .