The devouring Gray
(Book)

Series information from Goodreads.com.

"Four teenagers have the power to protect their town from a monster, but only if their families' secrets do not destroy them first." --,(Source of summary not specified)

Justin Hawthorne's bloodline has protected Four Paths for generations from the Gray-- a lifeless dimension that imprisons a brutal monster-- but Justin has not inherited his family's powers. Violet Saunders's family moves to Four Paths after her sister's death; her mother belongs to one of the revered founding families of the town. Harper Carlisle lost her hand to an accident that left her stranded in the Gray for days, and has vowed revenge on the person who abandoned her: Justin Hawthorne. The Gray is growing stronger every day, and when Violet accidentally unleashes the monster, the three teenagers must band together to unearth the dark truths behind their families' abilities. -- adapted from jacket