Lara Kemp's brother is dead. She's a wife and a mother, but she's lost in her grief and far too many days she finds herself curled up on her closet floor, unable to function. She's miserable and worst of all, she's lost all her memories of her brother and can only remember him through the stories other people share.

When Lara comes close to taking her own life, she and her husband take steps to get her the help she needs. They go on a much-needed visit to Lara's aunt in the small town of Grafton, Illinois, on the banks of the mighty Mississippi River. In search of something—anything—to help her overcome the pain and get back to her normal, unremarkable life, Lara stumbles upon an old book in an antique shop.

The book tells the story of a woman from a wealthy family in the 19th century, whose brother died in a fishing accident. Lara finds comfort in the book and her life slowly begins to return to a new normal. Months later, she reads the book again, but this time, the book is different. Lara thinks the book has changed. It appears to be small changes at first, and Lara chalks it up to just misremembering. But as she reads on, the story takes a dark, sinister turn and is nothing like the story she read the first time.

Soon, the terrifying things happening in the book begin to mirror the strange happenings in Lara's own life. With her husband and almost everyone around her convinced her experiences are a byproduct of her stress and grief, Lara is convinced it's real. Based on what happened in the book, Lara begins to hope it might hold the secret to recovering her memories of her brother, so she sets out to find out more.

Lara discovers that the story is real and that she and the women in her family are connected to the book in ways she never could have guessed. Refusing to back down in the face of the increasingly terrifying things happening around her, Lara enlists the help of Aunt Maisie and her friend Maryn, along with Amabel.