The Last House Guest, Megan Miranda

Avery Greers parent’s death in a car wreck left her broken and feral; Sadie Loman saved her. Avery, a Littleport Maine native and Sadie, pampered but smart rich girl are more like sisters than best friends. 

The Lomans own most of the rentals in this quaint seaside town and Avery manages those properties for them but Sadie’s apparent suicide drives a wedge between the Lomans of this world and the locals and over a year later as a memorial for Sadie looms, Avery stumbles across an even dirtier secret about her hometown; a secret that may have gotten her best friend murdered.