The adult narrator drives away from a funeral service and finds himself in front of the house where he grew up. The house that’s currently standing is the new house; his parents built it when the narrator was a teenager, after they knocked down their rambling old house. The narrator drives down the lane and comes to the farm at the end. He remembers that his friend Lettie lived here until she went to Australia. He greets the elderly woman in the farmhouse—she must be Mrs. Hempstock, Lettie’s mother, though she looks more like Lettie’s grandmother, Old Mrs. Hempstock—and heads out to the pond. As the narrator sits by this pond, he remembers that Lettie used to call it her “ocean.” Then, suddenly, the narrator remembers everything.
When the narrator is six years old, his parents fall on hard times; to make money, they rent out the narrator’s bedroom. The narrator is sad because the room is special to him, but he moves into his little sister’s bedroom. He and his sister fight about whether the door stays open at night (the narrator is terrified of the dark). Not long after, the narrator celebrates his seventh birthday—but no one comes to his party. After this, the narrator immerses himself in the books he receives and is thrilled when his father brings home a black kitten. He names the kitten Fluffy and they become best friends—until the opal miner, a new tenant, arrives. His taxi runs Fluffy over, and to replace the kitten, the opal miner gives the narrator a mean tomcat named Monster.
On the first day of the spring holidays, the narrator goes downstairs, excited for the SMASH! comic his father brought home. But when the narrator goes to get it from the car, he finds that the car is gone. The narrator’s father receives a call from the police: the stolen car was found at the end of the lane. The narrator’s father puts peanut butter on disappointingly burnt toast for the narrator, and they head down the lane with a police officer. When they find the car, they discover that the opal miner committed suicide inside it. A girl named Lettie appears and offers to take the narrator so he’ll be out of the way of the police. At the farmhouse, Lettie gives the narrator a bowl of porridge. She and Mrs. Hempstock seem to know all about the opal miner’s death. Lettie then takes the narrator out to the duck pond, which she calls the ocean—according to Lettie, she and her family traveled across it when she was a baby. There’s a dead fish on the water’s surface, and Lettie cuts the fish open and extracts a sixpence from it. Later, when the narrator asks, his father insists that oceans can’t be the size of a pond.
The next day, the narrator receives a letter in the mail informing him that he won 25 pounds through the Premium Bonds, and Mr. Wollery, the gardener, discovers a bottle of old coins. The narrator wakes the next morning from a nightmare and painfully coughs up a silver shilling, but he knows an adult won’t believe this happened to him. Outside, the narrator sees Lettie at the bottom of the drive. She says that someone—or something—is trying to give people money, and that this has to do with the opal miner’s death. Lettie tells the narrator about his neighbors’ money troubles and makes him pancakes at the farmhouse. Old Mrs. Hempstock inspects the narrator’s shilling, insists it’s brand-new, and allows the narrator to help her arrange daffodils. She and Mrs. Hempstock send Lettie and the narrator off to find “her.”
Lettie fashions herself a wand in the shape of a Y, and she and the narrator wander through the farmland. The narrator does as Lettie says and holds tight to her hand. He’s afraid and doesn’t believe they’re still on the farm—the sky is orange. They finally find “her:” a huge, flapping creature that looks like a rotting tent. The creature refuses to give Lettie her name and hurls a ball of cloth at the children. The narrator lets go of Lettie to catch the ball, and as he does, he feels a sharp pain in his foot. Lettie grabs the narrator’s hand and binds the creature “as a nameless thing.” As Lettie and the narrator head back, they reach a field of odd, snakelike plants. Lettie tells the narrator to pull one up: it’s a black kitten with a white spot on her ear. The kitten scampers away.
That night, the narrator inspects a hole in his foot that seems to have something inside it. He uses tweezers and hot water to extract a long gray and pink worm. It looks infected, and it breaks with a tiny bit still inside the narrator. He washes the worm down the drain. The next morning, the narrator’s mother informs him that she just got a job, so they’re getting a new nanny named Ursula. When the narrator comes to the kitchen for lunch, he finds his mother and sister with Ursula, a pretty blond woman wearing gray and pink. She’s terrifying to the narrator, but his sister and mother think she’s fantastic. The narrator is sure that Ursula’s arrival is his fault. Later, when the narrator’s parents are gone, Ursula informs the narrator that he can’t leave the property without her. She thwarts his attempt to sneak away and says that no one will believe anything he says. He refuses to eat anything Ursula makes and notices at dinner that his father seems to make jokes just for Ursula. That night, when the narrator’s mother is in town for a charity meeting, Ursula flirts with his father.
The next morning, the narrator’s parents leave before the narrator wakes up. His father gets home early and shows Ursula around the gardens. The narrator is afraid to approach—he fears his father will be upset with him—and sees his father put a hand on Ursula’s bottom. The narrator’s mother is away for dinner and again, the narrator refuses to eat Ursula’s cooking. His father gets angry, so the narrator tries to lock himself in the bathroom—but his father knocks the door down, draws a cold bath, and holds the narrator underwater. After this ordeal, Ursula locks the narrator in his bedroom. Knowing that Ursula won’t expect him to try to escape now, the narrator slips out the window and down the drainpipe. As he passes the drawing room, he witnesses his father and Ursula having sex, though he doesn’t understand what he’s seeing. He does understand that this means his father isn’t trustworthy. The narrator runs down the lane barefoot and cuts through fields until an electric fence shocks him. Ursula appears, floating with lightning in the stormy sky, and tells the narrator that she’ll make his father drown him every night—and then she’ll put the narrator in the attic until she’s ready to kill him. The narrator falls. Lettie appears, fearlessly tells Ursula to leave, and takes the narrator’s hand. Lettie offers to send Ursula back home, but Ursula refuses. She dissolves in golden light, and Lettie takes the narrator to the farmhouse.
At the house, Mrs. Hempstock and Old Mrs. Hempstock draw the narrator a bath and give him supper. Old Mrs. Hempstock knows that the narrator’s parents are coming to fetch him. To keep the narrator safe and out of Ursula’s hands, they decide to use “snip and cut.” Old Mrs. Hempstock cuts an irregular shape out of the narrator’s dressing gown, and when she finishes sewing it back in, just as the narrator’s parents enter the kitchen, the narrator’s father forgets the bathtub incident. The narrator’s parents agree that the narrator can stay the night and leave. Suddenly, the narrator’s foot feels like it’s on fire. Old Mrs. Hempstock inspects the narrator’s foot and declares that the hole is Ursula’s way home. She extracts the tunnel and puts it in a jam jar, though the narrator still feels like there’s a chip of ice in his heart. Lettie shows the narrator to bed, and the kitten he found earlier sleeps with him.
Over breakfast the next morning, Mrs. Hempstock says that she can’t hate Ursula—Ursula is just doing what her kind does. Lettie arrives with a shopping bag of broken toys and then leads the narrator to the ocean. There, Lettie asks the narrator what he thinks Ursula is afraid of and tells him a secret: adults all look like children on the inside. She says that she knows what Ursula is afraid of, and that she’s afraid of them too. They head for the narrator’s house, where Lettie drops broken toys around the property line. She drops a toy on each stair as they head up to the narrator’s old bedroom. Ursula refuses to cooperate. She runs away from Lettie but can’t leave the property; the toys keep her from doing so. Ursula begins to cry when she realizes that Lettie called “the cleaners.” She insists she’s ready to go home, pulls her tunnel out of the jam jar, and tries to go through—but when she realizes the end is still inside the narrator, she turns into her canvas self and lifts the narrator high above the ground. The cleaners—huge vulture-like creatures called the hunger birds—arrive and begin to eat Ursula and her tunnel. Then, they turn to the narrator and insist they must also eat his heart. Lettie leads the narrator to a protective circle called a fairy ring, instructs him to stay inside no matter what, and leaves.
The hunger birds gather around the ring. The opal miner, the narrator’s sister, his father, Ursula, and Lettie all appear in turn. They tell him that he’s alone and that no one loves him. The narrator feels as though he’d wait forever for Lettie; she’s his friend, and he trusts her. Lettie arrives with a heavy bucket containing some of the “ocean” water and helps the narrator step into the bucket. The narrator finds himself deep underwater, where he suddenly knows everything about the world. In this place, Lettie looks like silk and candles—but the narrator realizes that he can’t know what he himself looks like. Lettie pulls him out of the water, and the narrator finds himself in the pond, aware that he doesn’t know everything anymore. Lettie informs him that if one wants to live in this world, one must give up on knowing everything.
As the narrator eats, Mrs. Hempstock and Lettie discuss how to deal with the hunger birds. Old Mrs. Hempstock is napping—and she might nap for the next century. The narrator is scared he’s going to die, but Mrs. Hempstock assures him he’ll be fine. He takes Lettie’s hand and promises himself he won’t let go. They walk to the edge of the property, and the hunger birds huddle on the other side of the line. They ask for the narrator, and when the Hempstocks won’t give him up, they begin to eat everything in the outside world. When they eat something, only gray static remains. Terrified but certain he can’t let the birds destroy the world, the narrator races to the edge of the property. Though he can almost remember the feeling of the birds tearing out his heart, Lettie throws herself on top of the narrator and screams. Old Mrs. Hempstock, suddenly young and imposing, scolds the birds as Mrs. Hempstock gathers the narrator and Lettie in her arms. When the birds are gone, Mrs. Hempstock carries Lettie’s body to the pond. As the pond transforms into a true ocean, Old Mrs. Hempstock assures the narrator that Lettie is just hurt and needs to heal. A tsunami gathers and crashes down over Lettie’s body. Then, Mrs. Hempstock takes the narrator home, and the narrator promptly forgets everything that just happened— thinks he had a good time at Lettie’s going-away party before she moved to Australia. A month later, a black kitten with a white ear shows up. The narrator names her Ocean.
Back in the present, Old Mrs. Hempstock sits down beside the narrator. She says that what he remembers is probably true, but no two people remember the same thing—and she also says that the narrator comes here whenever life seems hard. Mrs. Hempstock appears and says that the narrator comes because Lettie, still in the ocean, wants to keep up with the narrator’s life and see if her sacrifice was worth it—she couldn’t allow the hunger birds to eat the narrator’s heart. The narrator is also surprised to see that Ocean is here on the farm, still alive. The narrator bids Old Mrs. Hempstock goodbye, asks her to say hi to Lettie the next time she writes from Australia, and drives away.