This man, who is investigating the contents of the valley, takes his suit off and takes a bath in what is revealed to be radioactive water. When my parents refused to do this, saying the safest place to be if a nuclear bomb fell was right underneath it, I knew I was doomed. She lives with her dog, Faro, in a remote valley and, despite her desperate circumstances, is resourceful, calm and determined.

Loomis soon begins to use Ann's cousin's dog, Faro, to track her and eventually (rather unsuccessfully) shoots her.The final word in Zechariah proclaims that on the Day of the Lord "in that day there shall be no more the Canaanite in the house of the LORD of hosts," [21] proclaiming the need for purity in the Temple, which would come when God judges at the end of time. Ann comes to believe the dreams may be true and Loomis is insane, so she plans to steal the safe-suit and find her dream valley. By allowing difficult things into their stories, I’ve discovered that the precious things have space to buzz and hum and sing. Doors taken from their hinges and propped against an interior wall offered good protection apparently.

During the exile, many Judahites and Benjamites were taken to Babylon, where the prophets told them to make their homes, [4] suggesting they would spend a long period of time there. It is revealed that, as a child, Ann had owned a Biblical ABC book which mentioned the prophet Zachariah. 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. His explanation that they have to plan "as if this valley is the whole world and we are starting a colony," makes her uneasy.

Loomis answers that he has no choice but to accept her proposal, though he hopes she will reconsider and "act more like an adult and less like a schoolgirl". Moreover, she decides to kill Faro to prevent Loomis from tracking her, though she is later unable to do so.