In the long, hot Illinois summer of 1973, insecure, motherless Jamie falls under the dangerous spell of her older, more worldly cousin Fawn, who's come to stay with Jamie and her uncle as penance for committing an "unmentionable act".
It is a time of awakenings and corruptions, of tragedy and loss, as Jamie slowly discovers the extent to which Fawn will use anything and anyone to further her own ends—and recognizes, perhaps too late, her own complicity in the disaster that takes shape around them.