Two Can Keep a Secret Book by Karen M. McManus

The follow up YA thriller from the author of the international bestseller One of Us is Lying.
A perfect town is hiding secrets. Secrets that somebody would kill to keep hidden.
Ellery’s never been to Echo Ridge, but she’s heard all about it.
It’s where her aunt went missing at age sixteen, never to return. Where a Homecoming Queen’s murder five years ago made national news.
And now she has to live there with her estranged grandmother, after her mother lands in rehab.
Malcolm grew up in the shadow of the Homecoming Queen’s death.
His older brother was the prime suspect and left Echo Ridge in disgrace.
But now he’s back- just as mysterious threats appear around town, hinting that a killer will strike again.
Then another girl disappears.
As Ellery and Malcolm race to unravel what happened, they realise every secret has layers in Echo Ridge.