Nat is a solitary farmworker living on a peninsula in Cornwall with his family. He receives a pension for an unspecified wartime disability and prefers working alone, which affords him time to observe nature closely. His past experiences surviving the Blitz in Plymouth give him a practical, deeply ingrained understanding of how to prepare for an aerial siege.

Mrs. Hocken is an industrious homemaker who coordinates closely with her husband to maintain their cottage in 1950s Cornwall. She possesses a cautious nature and prefers to keep her family together rather than face isolation. Though she fears the inexplicable natural events occurring around them, she works hard to keep her children calm and maintain hope for outside intervention.

Mr. Trigg is a cheerful, easy-going farmer and established landowner who employs Nat. He represents the comfortable, relatively secure British middle class of the 1950s. When faced with strange and threatening reports about the local wildlife, he responds with bravado and jokes, preferring to treat the situation as an opportunity for hunting rather than a genuine danger.

Mrs. Trigg is the broad, good-tempered wife of the local farmer. She maintains a traditional, comfortable rural home and enjoys discussing everyday matters and radio broadcasts. She possesses a highly rational but incurious mind, immediately seeking logical, mundane explanations for events that defy natural laws.

Jill is Nat's young daughter, a sensitive and caring girl who rides the bus to the local school alongside children from the nearby council houses. Despite experiencing a frightening event in her own bedroom, her childlike perspective allows her to temporarily forget her fear and focus on normal daily routines.

Johnny is Nat's toddler-aged son. Because of his small size and limited understanding of the world, he is the most vulnerable member of the household. He views the attacking creatures with innocent confusion rather than fully comprehending their malicious intent.

Jim is the cowman who works at the Triggs' farm alongside Nat. Although he occupies a similar social class as Nat, he displays a distinct lack of interest in his coworker's warnings. He focuses squarely on his agricultural duties and views Nat with some suspicion because of Nat's intellectual pursuits.