Ted and May Hocken move to a small island town called Gull Island with their two daughters, seeking solace after a family tragedy. Ted, a biology teacher, intends to write a book during their summer stay. The seemingly idyllic town begins to reveal strange occurrences when local birds exhibit increasingly aggressive behavior. Initially dismissing the birds’ unusual tendencies as seasonal anomalies, Ted's concerns grow as he witnesses the birds attacking residents, including May. Despite mounting evidence of the birds' hostility, the townspeople remain skeptical, attributing the attacks to random chance rather than acknowledging the unfolding menace.

As tension rises and the birds' attacks escalate in both frequency and severity, Ted seeks to understand the cause of their aggression. His inquiries are met with resistance, deepening the conflict between preserving normalcy and confronting the potential threat. Reluctantly teaming up with Frank, a local lighthouse keeper who has witnessed the birds’ behavior for years, Ted uncovers unsettling patterns linking human disruption to the avian aggression. Meanwhile, May attempts to maintain a semblance of normal life for their daughters amidst rising chaos. With communication severed and options dwindling, the family must confront a mounting terror that defies logical explanation. Their survival depends on deciphering the secret behind these deadly assaults as their initially peaceful summer transforms into a desperate struggle against nature's fury.