Alone on a seaside vacation, Leda (Olivia Colman) finds herself consumed by a young mother and her daughter as she watches them on the beach. Intrigued by their attractive relationship (and her strident, threatening family), Leda is overwhelmed by her own memories of the terror, confusion and intensity of early motherhood. An impulsive act leads Leda into the strange and ominous world of her own mind, where she is forced to confront the unconventional choices she made as a young mother and their consequences.
