Reality shift

When Kaylie Sturbridge, one of the popular crowd, starts acting strangely, flipping out in school and shouting about a dark thing following her, her friends shun her. Only Jonah seems to know what's going on, and he persuades Shanna to work with him to help Kaylie. But can the two of them rid Kaylie of the entity that wants to take over? And can Shanna trust herself enough to do what Jonah needs her to?