Emily Stewart claims to stand between the living and the dead. During the summer of 1925, she and her 13-year-old twin brother wander aimlessly around their brother's estate. One day, Emily discovers that she can secretly crack her ankle in such a way that a sound appears to burst through the stillness of midair. Emily and Michael gather the neighbourhood children to fool them with these 'spirit knockings'. Soon, however, this game of contacting the dead creeps into a world of adults still reeling from World War I.