When Sis wakes up in her father's backyard, staring at a rickety old shed, she can't remember how she got there or even who she is. But she remembers Amy, the sister that disappeared long ago, the same sister that she now hears calling to her from the shed. When Sis enters the shed she discovers that Amy is only there in spirit, and she is speaking to her through a new body, and that body just happens to be a chainsaw.Amy reveals to Sis that she was murdered by a local crime ring and she needs Sis to seek revenge for her. Sis agrees to the task and as Amy guides her to the home of each man responsible, Sis uses Amy's new body to hack them to pieces.But the situation isn't as straightforward as it seems at first. As Sis comes face to face with each man, she finds herself in the middle of unfamiliar flashbacks that put her at the scene of a heinous crime of which she has no recollection. In time, she begins to believe that these are not her memories and Amy isn't telling her everything she needs to know.What lies ahead beyond the coming bloodbath is something darker and more disturbing than Sis could have imagined. Who is Amy? Who is Sis? And what connection do they both have to the men she's about to murder?And why is her sister now a telepathic chainsaw?