In early December, a normal autumn in a British coastal town turns suddenly wintry overnight. The day before, Nat Hocken notices an increase in the number of birds flocking around the farm where he works part-time due to a wartime disability. He and the farmer agree that there are more birds than usual and that they are behaving more boldly and agitatedly. Nat wonders if there’s an unseen force that warns the birds that winter is coming, thus triggering an instinct to find food and shelter. He notices all types of birds are affected and flocking in mass: starlings, robins, finches, larks, oystercatchers, redshank, curlew, and gulls. Nat reasons that the odd behavior is because the birds are searching for food. Yet he concedes that until this day, the weather has been mild, and the earth has remained plentiful where it had been plowed.

That first night, the winds shift, and an easterly wind brings extremely cold, dry gusts that toss the sea and freeze the ground. It howls down the chimneys of the Hockens’ home and rattles the cottage roof. As the Hocken family sleeps, the room grows chill, and Nat seeks warmth by drawing the blanket closer to him and his wife. About two o’clock in the morning, Nat hears a tapping at his bedroom window. When the tapping continues, Nat gets up to investigate. As he opens the window, a bird flutters in and jabs at his hands before flying back over the roof. He closes the window and returns to bed, wondering why a bird would forage for food or shelter at this time of night. The bird was frightened, he thinks, which is why it attacked him. Nat dozes back to sleep, but another tapping begins, more insistent this time. Nat’s wife awakens at the sound and asks him to stop whatever is making the noise. When Nat opens the window again, there are more birds. They swarm Nat and viciously attack his face. He shouts and flaps his arms at them, shooing them out of the window once more. He asks his wife if she saw or heard what happened, but she only mutters sleepily. 

Nat then hears the children cry out from their room. He lights a candle and goes to their bedroom. When he opens their door, the window is open, and a gust blows out the candle. In the dark, he hears wings beating and birds flying and thudding into the walls. He quickly ushers his children out of the room and closes the door. Nat uses a blanket to strike at the birds, but there are too many of them. Instead, he wraps the blanket around his head for protection and fights the birds in the dark. After a time, the birds’ attacks lessen and eventually stop. The reprieve seems to coincide with dawn and the first gray light of morning. Nat removes the blanket and sees fifty dead birds around him. He returns to his bedroom. His daughter Jill is asleep next to his wife, who holds their young son Johnny in her arms. Johnny’s face is bandaged, and Nat’s wife says Jill told her the birds cut him. Nat’s wife silently beseeches Nat for an explanation. He offers his theory that the birds are searching for food and shelter, but she tells him the weather only just turned cold and that the birds shouldn’t be hungry yet. Nat offers to make them tea.

The ordinary task of making the tea in the kitchen comforts Nat. Outside, the frozen ground has black frost, and the east wind has stripped the trees bare of leaves. The family eats breakfast, which calms the children. Jill suggests putting out breadcrumbs for the birds, so they won’t attack again, and she prepares to go to school. His wife gives Nat a knowing look, and he walks Jill to the bus stop. Jill has forgotten the birds. She dances along the path and asks her father if it will snow. Nat explains it will be a black winter, without snow, and watches for birds in the hedges and bushes. There are none. At the bus stop, Jill runs to meet her friends and chats with them until the bus comes. Once Nat is sure Jill is safe on the bus, he walks to the farm.

At the farm, Nat sees Jim, the cowman. Jim reminds Nat that the farmer, Mr. Trigg, has gone to the market because it is Tuesday. Nat tells the tale of the bird attack to Mrs. Trigg, who humors Nat but teases him that maybe he imagined the birds after a night out. Nat insists, stating there are fifty dead birds in his cottage, and Mrs. Trigg suggests they are foreign birds that arrived from the Arctic Circle. After his frustrating conversation with Mrs. Trigg, Nat talks with Jim, who also doubts his story. Nat recalls the air raids he witnessed in Plymouth when he was younger and thinks the birds’ attack is similar. Back at his cottage, his wife asks him to clear the dead birds out of the bedroom. Nat notes they are ordinary birds he might see in the hedgerows and marvels at the damage their small beaks have made. He gathers the dead birds and puts them in a bag. 

Outside, Nat realizes the ground is too frozen to dig a hole for the dead birds, so he walks down to the beach. As he opens the bag to dump the birds in a hole in the sand, the powerful east wind catches and scatters them. Nat watches the rough waves and realizes that the waves aren’t white capped. Instead, thousands of gulls, tightly packed against one another, surf the waves. Nat thinks the gulls look like they are waiting for some signal. On his walk home, Nat wonders if he should notify someone and if so, whom. He decides against calling the police because he thinks they won’t believe him.

When he returns to the cottage, his wife shares a news bulletin she heard on the wireless and wrote down for him. Nat reads the statement and feels vindicated. The news has reported birds attacking people across the British Isles. The announcer suggests boarding windows, doors, and chimneys, and Nat gets his tools from the drawer. His wife doubts that birds such as sparrows and robins could do much damage, but Nat is more worried about the gulls than the small birds. Upstairs, he gets to work boarding the windows and recalls creating blackout boards and a shelter for his mother in Plymouth during the war. Nat darkly notes that these precautions failed to help in the end. Nat joins his wife and they listen to the news. It is the same news but with additional details about the London traffic and crowds of people watching the birds. The broadcaster states the birds are behaving unnaturally because of the cold and hunger. Nat is unnerved by the announcer’s light tone. He imagines London residents will have watch parties tonight instead of making preparations to protect themselves.

Nat boards the downstairs windows despite his wife’s complaints. She says the Army should come out and shoot the birds, but Nat recognizes the futility of her suggestion. He asks about their food supply, which puzzles his wife because shopping day is not until tomorrow. Nat continues boarding the cottage and making mental checklists of supplies. A little before three o’clock, the sky grows dark as the birds flock together once again. The rough sea drums at the shore. Nat tells his wife to stay indoors with their son while Nat goes to the bus stop to meet his daughter. Nat selects a hoe from his toolshed to carry with him as a weapon. As Nat waits for his daughter at the bus stop, he witnesses a large, dark smudge grow into a cloud. It is an enormous flock of birds. The flock breaks apart into squadrons of birds all of which fly quickly inland. Nat gets the feeling these birds are on a mission. He further concludes that these birds are going inland to attack the towns and believes the gulls will stay behind to attack the coast.

Nat calls the exchange from a call box near the bus stop to report his observations about the birds and gulls. The woman on the other end sounds disinterested, and Nat imagines her watching the birds that evening with her date. When the children get off the bus, they laugh because Nat is carrying a hoe. He tells the other children to go straight home. As he and Jill walk home, the gulls circle the fields in silence. Nat urges Jill to hurry and takes her hand. The gulls break off into squadrons like the other birds who flew inland. To gain speed, Nat carries Jill on his back, but this slows him down. Jill notices his worry and gets frightened. They pass by the farm when Mr. Trigg backs his car out of the garage. Nat asks him to drive Jill home. Mr. Trigg seems cheerful and invites Nat to a shooting match with him and Jim, to scare off the birds. Nat refuses both the invitation and an offer to take a gun. Mr. Trigg drives Jill home. Nat deduces the farm is the birds’ target, but he increases his speed to get home. On his way back, Mr. Trigg stops the car to again ask Nat to shoot with him later, but Nat refuses. He asks if Mr. Trigg has boarded the farmhouse, and Mr. Trigg dismisses the idea. Mr. Trigg says Nat is skittish and tells him to come by in the morning for a breakfast of gull.

Nat rushes toward his cottage. He has one field left to cross when the birds begin swooping down to attack him. The hoe is useless, so Nat tosses it. He protects his eyes, warding off the birds with his arms and hands. He is grateful the birds have not yet learned the tactics that would overwhelm him. His hands are bleeding when he arrives at the cottage and he pounds on the door. Moments before his wife opens the door, a gannet dives toward Nat. The door opens, and Nat stumbles inside, slamming the door. Nat hears the gannet thud violently behind the door.

Nat’s wife bandages his hands, and he comforts the crying children, saying he only has a few scratches. Nat and his wife whisper about what to do. In the kitchen, Jill is anxious because she hears the birds. They hear scratches, wings beating, muffled sounds, and thuds of birds crashing in the cottage. Nat assures his daughter that his work boarding the windows will prevent the birds from getting in. They turn on the wireless to help drown the sound of the birds. Upstairs, Nat hears birds on the roof. He decides the family will sleep in the kitchen, and he brings the mattresses down. He explains they will play camp in the kitchen. They rearrange the furniture to make room for the mattresses, and Nat compares the arrangement to an air-raid shelter. Dance music plays over the wireless instead of the usual programs. At six o’clock, the news announcer comes on the air with an update. A national emergency has been declared. No further programs will be broadcast until seven o’clock tomorrow morning.

Without further programs to listen to, the sound of the birds causes anxiety again in the household. Nat suggests an early supper to keep everyone busy and distracted. After their meal, a droning noise joins the sound of the scuffling birds. Airplanes have arrived, probably the Airforce. Nat’s wife says she hears gun shots and believes they are shooting the birds, but quickly they hear a crash. His wife asks if the planes are dropping bombs. Nat doubts it, but he does not share his certain conclusion that the planes have crashed due to suicidal birds flying into the propellers. Nat’s wife prepares the children for bed, and he goes upstairs. Nat believes the best scientists are working on the problem, which he thinks is better than the government trying to create a solution. The bedrooms are now quiet, and Nat considers that the birds have left to regroup. He hears the waves on the beach and remembers the gulls riding the waves until the tide came in. He deduces that the battle has ceased because the tide has gone out and calculates the hours until the birds will return with the high tide.

Nat considers his options and wants to go check on the Triggs at the farm, but his wife says she does not want him going out. Nat steps outside and evaluates the situation. There are dead birds everywhere and no signs of life. Nat stacks dead birds on the windowsills of the cottage as extra protection against the next attack. As he works, he notices every window has cracks. Back inside, he and his wife have hot cocoa before laying down to sleep. Nat has fitful dreams where he has forgotten to do something important. When his wife wakes him because of a bad smell, Nat remembers. He forgot to stoke the fire to keep it burning. As a result, birds are trying to get down the chimney and singing their feathers from the low-burning coals. Nat adds sticks, paper, and paraffin to the embers. Flames roar up the chimney, and Nat rakes away charred birds as they drop into the fire. Nat hopes that a fire won’t catch in the chimney, and the children wake crying and afraid. 

It’s only three o’clock in the morning, and the tide won’t turn for another four hours. Nat’s wife makes tea and cocoa to keep everyone busy. Nat determines the chimney is clear and asks Jill to bring more sticks, but she does not want to go near the charred birds. Johnny yells at the birds to stop, and Nat encourages his fighting spirit. The family makes a game of cheering when they hear a suicide bird thud and fall to the ground. Nat smokes his second-to-last cigarette and contemplates the birds’ persistence. He admires them for a while until he recognizes a new sound, one of a sharper beak against the door. Nat goes upstairs to evaluate if any furniture could help reinforce the door. He hears birds inside the children’s bedroom.

At five-thirty, the family has breakfast. Nat watches the clock, anticipating the tide’s next turn. Near seven o’clock, his wife reminds him that the wireless should come to life again, but only static comes through. Nat assures her they heard wrong and that the broadcast will come on at eight o’clock. Once the morning light appears, the noise of the birds lessens. The children fall asleep. Nat prepares to go to the farm, but his wife protests he should stay for the news. He says there won’t be any news, that they must rely on themselves, and they need supplies. Outside, the land birds watch Nat in the garden. He returns to the cottage to make repairs before going to the farm to get food and supplies. The entire family gets dressed for the cold weather and brings baskets and Johnny’s baby carriage. The birds’ silent stares scare Jill.

Just before they reach the farm, Nat tells his wife to stay with the children in the bushes. She protests again, but Nat remains firm. At the farm, Nat finds the dead bodies of Jim, Mr. Trigg, and Mrs. Trigg. The cows are mooing because no one has milked them. Nat brings the car for his wife and children to sit in because he does not want them to see the bodies. They make three trips with the car to bring food and supplies to their cottage. On the last trip, Nat checks the phone box, but the line is dead. There’s no smoke rising from the chimneys of the nearby houses. Birds watch him from the fields, and Nat thinks this would be the time for the Army to go on the offensive, while the birds are in a stupor from gorging all night. Nat’s wife urges him to drive quickly so the children won’t notice a dead postal worker in the lane. There’s only an hour until the tide turns again. Nat opts to eat a cold dinner so he can get to work reinforcing the cottage’s barricades.

As he works, Nat looks to the sky for airplanes but knows they are not coming. He sees something far out at sea, and thinks it might be the Navy, but it is not. Once more, it is the gulls gathering. The tide has turned again. Inside, the family eats. Although it’s only two o’clock in the afternoon, Johnny remarks that it’s nighttime. The wireless is still silent. Nat’s wife can’t find any station, not even other European stations. Nat wonders if the birds are a problem across Europe. As they eat in silence, his wife wonders aloud if the Americans might intervene. 

The birds begin to scratch and peck at the cottage windows and doors again. Nat eats his soup and plans to have the whole family pitch in to organize the supplies they brought. This will keep everyone busy and tire them out so they can go to bed early. He has a new idea for the windows. He will add barbed wire he brought from the farm, though he will have to do the work in the dark at the next turn of the tide. As he listens to the small birds at the windows and the hawks at the door, he wonders what evolutionary process caused the birds to attack humans with machine-like precision. Nat lights his last cigarette, noting he should have remembered to get some from the farm. He turns on the silent wireless and tosses the empty cigarette packet onto the fire.