The following version of this book was used to create the guide: Magee, Audrey. The Colony. Farrar, Straus and Giroux, 2022.

The Colony begins from the perspective of an English painter named Lloyd. The year is 1979, and Lloyd is traveling to a remote island off the coast of Ireland in order, he asserts, to paint the cliffs there. Lloyd is steadfast in his insistence that he be ferried to the island the traditional way (by small rowboat) and live in total cultural immersion so as to gather for himself the truest possible experience of the island's culture. His efforts to assimilate are stymied, however, by two factors: in the first place, his pedantic demands for extremely particularized conditions in order to complete his art, and in the second, the fact that Lloyd does not speak Irish like the majority of the island's inhabitants. Though he is treated cordially enough by the two men who ferry him to the island, Micheál and Francis, the islanders apprehend Lloyd coldly and suspiciously, and as soon as he is settled in his cottage the islanders begin to gossip about him unfavorably.

The suspicion of the islanders only grows when Lloyd begins casually sketching the islanders themselves despite Francis's request that he stick to capturing the scenery. Lloyd is aware of the acutely cold reception the islanders are giving him, and he begins to feel insecure about his inability to penetrate the culture. This feeling of insecurity is only exacerbated by the unexpected arrival of a French linguist named Masson. Masson has been coming to the island perennially to study and preserve the Irish language for the past several years, and he is as displeased to see Lloyd as Lloyd is to see him. Lloyd is irritated by the fact that Masson's cottage is directly next to his, and ultimately requests a move to a small, unfurnished, poorly weather-proofed signaling hut on the far side of the island so as to avoid Masson's loud conversations in Irish. Masson, for his part, is near the end of his study, and regards the presence of an English speaker on the island as a veritable crisis for the delicate ecosystem in which he has attempted to observe one of the last pockets of Ireland in which the native language is still spoken. Lloyd and Masson immediately begin to butt heads; Masson mocks Lloyd's paintings as derivative, while Lloyd insists that Masson's project is a useless one, and that Masson (and France) is just as much a "colonizer" as he is. The theatrics between the two interlopers on the island quickly become irritating to Micheál, Francis, Mairéad, and Bean Uí Néill, but Micheál maintains that they stand to make twice as much money as they might usually by accommodating two summer visitors.

As Lloyd and Masson set about their work, the youngest boy on the island, James, becomes increasingly fascinated by Lloyd. James eagerly seeks an escape from the limited world of the island, and has a knack for painting; naturally, he begins to shadow Lloyd as Lloyd sets about his work. Aside from his mother, Mairéad, the islanders are eager to train James to be a fisherman so that he can provide food for them. James, however, is resistant to this idea, haunted by the memory of his drowned father and resolute in his desire to escape the generational cycles of the small island. Indeed, even his choice of name (which Masson frequently argues with him about) signals his soi-disant difference from his fellow islanders; he opts for the English James as opposed to the Irish Séamus. Though Lloyd is initially somewhat irritated by James's presence, he quickly realizes that the boy is a useful conduit to his learning more about the ecology and culture of the island, and he slowly takes James under his wing as something of an apprentice, offering him canvases, paints, and pencils with which to complete his work. James, for his part, begins assisting Lloyd in his efforts to render the scenery of the island; he corrects the proportions of Lloyd's birds, and Lloyd's depiction of light upon the water. As the other islanders become more and more suspicious of Lloyd's intentions, James increasingly becomes his most steadfast ally, and the pair form a friendship.

Meanwhile, Mairéad begins cautiously interacting with Lloyd, who wants her to pose for him as a model. Mairéad is also eager to escape the poverty of the island, and is particularly vexed by the lecherous advances of her brother-in-law, Francis, who hopes to marry her now that she has been widowed by her husband (and James's father) Liam. Though Mairéad is initially skittish around Lloyd, she slowly becomes more and more comfortable with their meetings, and begins imagining her image being revered and celebrated throughout England. She begins posing in increasingly vulnerable positions for Lloyd, eventually shedding her clothing almost entirely, and she becomes the centerpiece of the large mural that Lloyd decides will be his magnum opus.

Things begin to change as Lloyd slowly realizes that James is a more talented artist than he is. Lloyd is haunted by his relationship with his wife, who has effectively cuckolded him with another artist she considers more talented and more innovative. Masson's taunts about the derivative quality of Lloyd's work and the realization that the unschooled island boy he has taken under his wing possesses more natural talent than he does lead to a shift in Lloyd's attitude. He begins becoming cagier about the possibility of bringing James to England with him to study as his apprentice, and he even edits his mural to portray James as a fisherman instead of a painter, a petty gesture whose implications are not lost on James. James also realizes that Lloyd has borrowed so heavily from his paintings that Lloyd's depictions of the islanders are almost carbon copies of James's. When James confronts Lloyd about this creative theft, Lloyd brushes him off, and tells him that given the violence taking place along the Anglo-Irish border it would not be a good time for James to come to England with him. Meanwhile, Masson begins to investigate Mairéad's visits to Lloyd's hut and quickly realizes that she has been posing naked for him, a revelation that makes Masson jealous, as he has been sleeping with Mairéad. As retribution, he tells Francis and Mairéad's mother, Bean Uí Néill, about her trysts. The consequences are swift and devastating; as the novel draws to a close, Mairéad realizes that her mother has turned against her and she will be forced to marry Francis. When Lloyd departs the island, he does so without James or James's paintings, leaving the boy to languish.