[1] Set in the continental territory of the United States, it is written from the first-person perspective as the diary of sixteen-year-old Ann Burden.

According to Sally Conly in summer 1972, Z for Zachariah would be her husband's "second adult novel" following the months-old science fiction thriller A Report from Group 17.

She discovers that the stranger is John Loomis, a chemist who helped design a prototype radiation-proof "safe-suit" at an underground lab near Ithaca, New York.

As Loomis recovers, Ann is taken aback when he forbids her to touch the safe-suit and begins giving her orders on farming and managing resources.

[5] Her uneasiness increases when she asks if he was ever married, and he grabs her hand roughly, rebuking her when she accidentally hits him while trying to regain her balance.

The valley is approximately 4 miles long, from Burden Hill in the north to an S-shaped pass in the south called "the gap".

A smaller stream originates from a deep spring on an eastern hillside and feeds a small lake with fish that provide a food source for Ann.

[11] Loomis calls it a meteorological enclave created by an inversion (i.e., air only rising, not falling), but he views its existence as so unlikely that it is only a theoretical possibility.

[12] Seeing the story as a conflict between an innocent girl and a domineering male scientist bent on controlling the valley, reviewers have found themes such as the destructiveness of science (at least when it is separated from conscience), the corrupting effect of the desire for power, and the moral value of individual freedom.

Ann's sensitivity and love of nature are viewed as contrasting with Loomis' callous reasoning and selfish compulsion to take control.

"[13] Reviews the same year in The Junior Bookshelf[14] and Times Literary Supplement[15] described Ann as an unwilling Eve who "finally refuses to begin the whole story over again."

In February 1984, the BBC presented a film adaptation for its Play for Today series in which the setting was changed from America to Wales.

Z for Zachariah, a 2015 film adaptation of the novel premiered in January 2015 with financing from Creative Artists Agency (CAA) and Material Pictures.

Eschewing the central Adam/Eve theme and its deconstruction of abusive and controlling relationships, it adds a third character and involves a love triangle.

[16][17][18] Filming took place on New Zealand's Banks Peninsula[19] and in the small former coal mining town of Welch, West Virginia.