An old Roman senator, contemplative at his late stage of life, embarks on what will likely be his last endeavour: the retelling of the story of human creation. He recounts the history of the Clefts, an ancient community of women living in an Edenic, coastal wilderness, confined within the valley of an overshadowing mountain. The Clefts have no need nor knowledge of men -- childbirth is controlled, like the tides that lap around their feet, through the cycles of the moon, and their children are always female. But with the unheralded birth of a strange, new child -- a boy -- the harmony of their community is suddenly thrown into jeopardy.
At first, in their ignorance, the Clefts are awestruck by the seemingly malformed child, but as more and more of these threateningly unfamiliar males appear, now unfavourably nicknamed Squirts, they are rejected, and are exposed on the nearby mountainside; sacrificed to the patrolling eagles overhead, the sentinels of their female haven. Unbeknownst tot he Clefts, however, these baby males survive, aided by the very eagles sent to kill them, and thrive on their own on the other side of the mountain. It is not until an unusually curious young Cleft named Maire goes beyond the geographical, and emotional, divide of the mountain that this disquieting fact is uncovered -- a discover that forces the Clefts to accept and realign themselves to the prospect of a now shared world, and the possible vengeance of the wronged males.