Here there are monsters
(Book)

Sixteen-year-old Skye must confront her most savage secrets to save her missing thirteen-year-old sister, Deirdre, from stick-and-bone monsters that have come to life in the woods behind their new home.

Skye believes that moving across the country will be the perfect chance to start over. In their isolated new neighborhood Skye manages to fit in, but her younger sister Deirdre withdraws from everyone, becoming fixated on the swampy woods behind their house and building monstrous sculptures out of sticks and bones. Then Deirdre disappears. Now something awful comes scratching at Skye's window in the middle of the night, claiming she's the only one who can save Deirdre. And Skye will stop at nothing to bring her sister home. -- adapted from back cover