Thirteen years after a series of shocking and unexplained events shattered the lives of a family living alone on the marshes of East Sussex, two women arrange to meet. One is the daughter of the family and the other, a scientist who seeks to uncover the truth about Marshfell Cottage and the disturbing events that have defined their lives ever since. But as the evening progresses, an uncanny energy fizzes in the room, interfering with sound and light, memory and reality. Is it the cottage that is haunted? Or is there something much more unknowable that needs their help?