The Mammoth (The Mammoth #3)

Faced with a lake of the dead and memories of her mother, Jess isn't sure which she wants to escape more. A desperate drive through the endless forest solves one of them for Jess and the others, but the eerie Broke Tree Valley isn't going to let them off that easily, because although Olivia seems to know the way, that path leads not only straight to the very real problem of some felons with guns but a supernatural entity, the titanic ghost in the forest known as the Mammoth.