There are two things seventeen-year-old Emma Carver is known for: the fact that she grew up beside a sprawling bog, and that her sister went missing over a year ago. No leads, no clues, no trace. Having spent much of the past year trying to heal from the tragedy in the golden sun of the West Coast, Emma has just returned to Maine, feeling like three thousand miles wasn't enough to escape the ghosts of her past, both literal and metaphorical.
Her return to New England brings her little comfort or closure. Her father seems convinced she should have stayed away, and the family's old farmhouse that stands by the bog—known as the Moss—seems particularly upset to see her again. Darkly familiar shadows and specters fill her dreams, her periphery, the quiet spaces between her thoughts.
But something else is following her, pulling her in to the Moss, and it's growing stronger by the day. With the help of a local boy, who had confessed his feelings for her just before she went away, Emma delves deeper and deeper into the mystery of the growing hauntings—and learns that not only might her sister still be alive, but if she's willing to put herself in grave danger, there might just be a chance to save her.