Cornwall, a coastal county in the south-east of England, is cold during the winter, but in early December there is a sudden cold snap making the weather even more frigid than usual. Nat Hocken has just returned from action in World War Two; he was wounded and is living on his military pension which he subsidizes by working part-time for a farm owner nearby. One day he notices that many of the birds that fly over the peninsula where he lives with his family are acting very strangely. Ned believes it is the extra cold weather that is making them behave this way.
That night, Ned hears a tap..tap...tap... on his bedroom window. When he goes to see what is making the noise he sees a bird, and when he opens the window the bird pecks aggressively at his hand, making it bleed. Throughout the night the avian invasion continues; there are birds swooping in and out of his children's bedrooms which scares them. However, in the morning, the birds leave the house, which makes Ned think that they were seeking warmth, out of the cold. He tells his wife as much too, calming her fears by telling her the birds are restless because of the changes in the weather.
Nobody he works with seems very impressed with his story of the birds flocking into his house. When he walks to the sea later he sees a line of seagulls sitting on the water waiting for the rising of the tide. Despite his co-workers' scepticism and disinterest in the birds, Ned learns that he is not alone in noticing their newly aggressive behavior. When he gets home he catches a report on the radio that states bird attacks all over Britain. Ned takes precautions. He boards up the windows of his house, and blocks the chimney so birds cannot enter that way either.
Nat picks his daughter Jill up from the bus stop after school and begins to shield her body with his to protect her from impending bird attacks. When he sees his boss, Mr Trigg, driving by in the car, he persuades him to give Jill a ride home.. Although Mr Trigg seems completely unbothered by the news reports and is actually looking forward to shooting at the birds if it becomes necessary. He offers Ned a ride as well but Ned declines. He walks home and manages to get into the house in the nick of time as a cloud of gulls begin to attack him with their vicious pointed beaks.
BBC Radio announces that a national state of emergency has been declared. People are told to stay in their homes because of the number of birds swooping to attack. In an unprecedented measure the radio station then goes off the air, and will resume broadcasting in the morning. It is believed that radio silence is imperative if safety is to be regained.
Nat realizes that the kitchen, being the most central room in the house, is also the safest, and so brings his family there to hide for the night. They hear sounds all through dinner a little like planes flying above them, and then it sounds like the planes are crashing. The attacks diminish and it occurs to Ned that they are only attacking at high tide.
The wireless broadcasts do not resume as promised, and radio silence continues. At low tide, Ned ventures out of the house to meet with his neighbors and pool their supplies. There are piles of dead birds everywhere and the birds who are still living don't attempt to attack but watch him from a distance. Ned can't find anyone; at the farm where he works he discovers the bodies of Mr Trigg and his wife, as well as their workman Jim. Further down the street he finds the body of the mailman. Ned realizes with a jolt that all of his neighbors have been killed by the birds.
Ned returns home as quickly as he can; at high tide the birds renew their attack and Ned smokes his last cigarette, as if preparing himself to face the inevitable.
