The narrator describes the landscape of England at the time of the story, with ogres haunting the forests and very few castles to be found. On the edge of one of the bogs found in the rural countryside, Axl and Beatrice, an elderly Briton couple, live together in a communal warren dug into a hillside. They live alone in one of the back rooms, far away from the communal fire, and are not allowed to have candles. Axl is awake and excited about a decision he has just made, but decides to keep it to himself until Beatrice wakes up. As he waits, Axl thinks about their lives in the warren and wonders if they have always lived as societal outcasts, relegated to the back corners and treated with little to no respect. Axl thinks about a problem that everyone seems to be having: they forget things that they should remember, even their own children or people who once lived among them.
Finally, Beatrice wakes up and Axl tells her that he’s decided they should go on a journey to their son’s village. They have not seen their son in many years, and can’t remember the details of why he chose to leave or even his name. Still, they are certain that he’s waiting for them and that they’ll be able to live with him when they get to his village. Beatrice agrees and, after talking to the pastor about their plan, they set out on their journey alone. It is dangerous to walk through parts of the English countryside because of the monsters that still live there, so Beatrice often asks Axl (who walks behind her) whether he’s still there. When it begins to rain, they take shelter in an abandoned house. Inside, they meet a boatman and an old woman who is about to slaughter a rabbit. The boatman hates the woman, who has been harassing him since he took her husband across the river to an island but left her behind. The island is a place where people can live in peace forever, but if they go alone then they may never run into another person there, even their loved ones. Only couples who are bound by true love and whose relationship is not characterized by anger, resentment, or indifference can go there together, according to the boatman. When the boatman tells the old woman to “look into her heart” and determine whether her bond with her husband was really strong enough for them to be taken to the island together, she refuses to answer him. Beatrice is particularly interested in this idea and wants to go there with Axl one day after they see their son.
When the rain stops, Axl and Beatrice leave the boatman and continue their journey until they reach a Saxon village where Beatrice often does trading. Not only will they stay the night at the village, but Beatrice wants to see a medicine woman who might give her medicine for a pain in her side she’s been experiencing. When they get there, however, the townspeople are on edge because a young boy, Edwin, had been kidnapped by ogres. Beatrice and Axl watch and listen to the uproar around them, taking notice of a haggard-looking man who is at the center of a group of people. Eventually, Beatrice notices Ivor, a Briton who serves as mayor of the town, and he tells her that the man they noticed, Wistan, is going to lead a group of men out to rescue Edwin. Because the town is so tense, Ivor invites Beatrice and Axl to stay at his home instead of having to go to the inn. At Ivor’s house, Beatrice, Axl, and Ivor discuss the mysterious mist that permeates the land and makes everyone forget. Ivor says he believes the mist has invaded because God has forgotten their pasts, and Beatrice soon adapts this theory and believes God is ashamed of something they did in the past and is willing them all to forget what it was. Ivor leaves the house to wait for Wistan’s return and so Beatrice and Axl can sleep. During the night, however, Edwin is found and returned, but his family turns against him because he was bitten by a mysterious creature. Ivor sends him to stay in a nearby barn until it’s safe.
When Axl wakes up, he sees Beatrice is still sleeping and feels a rush of tenderness mixed with an indecipherable sense of sadness. He pushes the sadness from his mind and waits for Beatrice to wake up. When she does awake, they get their stuff together and leave Ivor’s house to find breakfast and prepare to continue their journey. Wistan seems to remember Axl, but he can’t remember from where, and neither can Axl. While they talk, Ivor asks Beatrice and Axl if they’ll take Edwin with them because it’s not safe for him to stay in the village. They agree, and Wistan decides to journey with them for a little while. Beatrice wants to go to a monastery where the well-respected Father Jonus, a monk with a penchant for medicine, might have a cure for her pain. The group agrees and they set off together.
As Beatrice, Axl, Wistan, and Edwin walk along, they run into a band of Briton soldiers who are guarding a bridge they need to cross. Wistan foresees danger because he is a Saxon warrior sent on a mission by a Saxon leader to see how Saxons and Britons are getting along. He tells Beatrice and Axl to pretend that he is mute and mentally ill, and that Edwin is his brother in order to avoid suspicion. Going up to the soldiers to ask to pass, Beatrice and Axl convince the leader, a grey-haired soldier, that they are innocent farmers and are given permission to pass. Once they are far away from him, Wistan stops acting like a mute and they press on. A short time later, they run into a knight resting near a tree. Although Wistan resumes acting like a mute at first, he soon recognizes the knight as Sir Gawain, one of King Arthur’s nephews and most trusted knights. Sir Gawain and Wistan start talking about the past, although Wistan clearly can’t remember all of it. At one point, Wistan tells Sir Gawain to look at Axl and see if he remembers him. Sir Gawain looks taken aback, but says he doesn’t remember Axl. They continue talking until suddenly hearing someone coming: it is the grey-haired knight from before. This time, the knight, who is working for the Briton Lord Brennus, confronts Wistan and they duel. The grey-haired knight asks Sir Gawain for backup, but Sir Gawain refuses and Wistan easily defeats the knight. Sir Gawain agrees to help bury the body, but he and Wistan argue over Wistan’s mission of slaying the dragon Querig. Sir Gawain insists that it is his duty because King Arthur would have wanted him to, but is unable to get Wistan to promise not to kill the dragon himself.
Sir Gawain accompanies the group to the monastery, but leaves shortly after getting them there. Wistan is suspicious of what’s going on there, especially when Beatrice is told that she can’t see Father Jonus yet. As time passes, they discover a device that they fear the monks use to torture people. This is verified when Father Ninian, a silent monk, sneaks them in to see Father Jonus and they discover that he had been tortured. Father Jonus gives Beatrice medicine and makes something to treat Edwin’s bite before the group leaves him to rest. Wistan observes to Edwin that the monastery shows evidence of once being a Saxon stronghold with traps for Britons, proving past violence. That night, the group is woken up by Father Brian, who tells them that soldiers are everywhere looking for them and Wistan. While Wistan is left behind in a tower, the rest of the group is led to a secret tunnel. Once inside, Father Brian shuts them in, and they realize they’ve been trapped. Fortunately, Father Ninian warned Sir Gawain, who is waiting for them in the tunnels to protect them from the monster there. He successfully defeats the monster in the tunnels and the group gets out, but Edwin runs back to help Wistan.
After their escape from the monastery, Sir Gawain goes his own way and Axl and Beatrice head in what they believe is the direction of their son’s village. Following directions from Sir Gawain, Axl and Beatrice arrive at a river and convince a merchant there to lend them two large baskets that will help them float down the river and get to their son’s village faster. At this point, Beatrice is very weak and Axl is worried about her ability to continue on the journey. His concerns are made worse when they stop to help a woman in a boat and are attacked by pixies, who tell Axl to leave Beatrice behind. The pixies imply that this is what Alx himself wants to do because “there’s no cure to save [Beatrice]” and he will have to take care of her as she gets sicker. Axl, however, fights the pixies off, gets Beatrice, and escapes to safety. They continue walking and stumble upon a house in which three kids are living alone. The kids tell Beatrice and Axl that their parents have forgotten them, and they plan on killing Querig with a goat that has eaten enough of a poisonous plant that any monster who eats the goat will also die. The children convince Axl and Beatrice to bring the goat up the mountain to feed it to Querig—once Querig is dead, the mist will be lifted, and everyone’s memories will return.
Meanwhile, Edwin has found Wistan, who is injured but alive and tells Edwin he wants to train him to be a warrior. Wistan tells Edwin that he not only has the spirit of a warrior, but of a tracker, too, and can lead them to Querig, so they plan to go find and slay her together. On the way, Wistan tells Edwin that once they complete their mission, he needs to always remember to hate the Britons and that they have a duty to kill all of them, including women and children. Although Edwin doesn’t understand, he makes a promise to remember Wistan’s words.
On the way up the mountain, Axl and Beatrice run into Sir Gawain, who is also heading up to Querig’s lair. He says he is going to slay her and agrees to help Axl and Beatrice, along with the poisoned goat, get up there. Once they get there, they discover a giant’s cairn and decide to tie the goat up and rest for a while. As Axl ties up the goat, Sir Gawain whispers to Axl that he remembers the past and knows Axl made a treaty with the Saxons that King Arthur broke, and he criticizes Axl for yelling at King Arthur over the treaty. Axl doesn’t respond to this except to say that he wants the memories of his marriage back. Sir Gawain sees Wistan and Edwin coming and prepares to fight Wistan. When Wistan and Edwin get there, Edwin has been compelled forward by a mysterious force and is tied up next to the goat. Wistan insists on killing Querig, but Sir Gawain argues against it, saying she should be allowed to live out her life, ensuring continued forgetfulness (and peace) for Britons and Saxons for a little while longer. Wistan criticizes this idea and he and Sir Gawain duel. Wistan kills Sir Gawain and then goes to Querig and slays her, too. Afterward, he tells Axl that he remembers him from his childhood and knows Axl made the treaty that King Arthur broke. Wistan is beginning to regret what he’s done because war will ensue now that people’s memories will be restored, and he urges Axl and Beatrice to get out of the country as quickly as they can. Axl and Beatrice leave Wistan and Edwin with Querig and continue their journey.
Axl and Beatrice, who is even weaker than before, find shelter from a storm and discover that a boatman (the narrator) who can take them to the island from there. With their memories returning, they agree to take the test to see if they can go together. The boatman discovers that Beatrice once had an affair and that Axl had harbored a lot of resentment about it. Frustrated with them both, their son left home and died of the plague shortly thereafter. Axl had refused to take Beatrice to their son’s grave when they got word. The boatman says he can bring Beatrice to the island and will be back for Axl, but Axl, who remembers what the old woman they met earlier said about being left behind, is suspicious that the boatman might be lying. Still, Axl makes sure Beatrice is comfortable in the boat and tells her he loves her before walking back to shore. On his way, the boatman repeats that Axl should wait, but, without a word, Axl keeps walking away from him, having accepted that he and Beatrice will not dwell on the island together. Axl’s true motives in walking away—whether he believed that he and Beatrice were never actually going to be allowed to go to the island together, latent and residual anger at her for her past infidelity, the fact that it was simply not his time to die and go to the afterlife, or something else—is ultimately unclear.