It’s the early 1700s, and Susan Barton, an Englishwoman, has just been stranded on an island in the Atlantic Ocean. Though she at first believes the island to be deserted, Susan quickly encounters an older white man named Cruso and his Black servant, Friday, the sole survivors of a long-ago shipwreck. Susan laments her bad fortune to an unnamed reader: after two years spent in Bahia, Brazil, trying to find her kidnapped daughter, she had at last booked passage on a ship back to Europe—only to have the ship’s crew mutiny, killing the captain and casting her onto this island.
Though Cruso and Friday have built a sturdy encampment, Susan has trouble adjusting to life on the island. Cruso is gruff and rarely speaks, and Friday never talks at all; to Susan’s horror, she learns that he has had his tongue cut out under mysterious circumstances. Worst of all, the days are monotonous: the wind won’t stop howling, and all Cruso and Friday ever do is build terraces on the island, even though they have no crops to plant on the terraces.
After about a year, Cruso becomes deathly ill, getting feverish and delusional. For 12 days, Susan tends to Cruso while Friday distances himself, playing his flute non-stop. As Cruso’s fever breaks, he and Susan have a single sexual encounter, which Susan engages in more out of pity than desire. While Cruso struggles to shake his illness, a passing British ship discovers the islanders. Susan is elated and jumps on board, but Friday is more hesitant (and Cruso, still not in his right mind, does not even realize they are being rescued). Susan takes the name Mrs. Cruso to avoid a scandal—but Cruso dies before the ship can arrive in England.
Upon her arrival, Susan presents her castaway narrative to an author named Mr. Foe. In a series of letters, Susan asks Foe, a celebrated storyteller, for money to support herself and Friday; she has given Foe permission to turn her story into a book, which she hopes will bring fame and riches to them all. In her letters, Susan struggles to cope with Friday’s silence, reflecting on the importance of storytelling and communication. She addresses Mr. Foe’s questions about the island; he is particularly curious about whether or not Friday ever engaged in cannibalism, though Susan assures him no such thing happened.
Susan stops hearing back from Mr. Foe, and she becomes increasingly anxious about how she will support herself and Friday. When she goes to Foe’s house, she sees that two bailiffs have taken up residence, waiting to arrest Mr. Foe. Susan tries to learn about Foe’s whereabouts from his maid Mrs. Thrush, but she is unsuccessful.
April becomes May, and still there is no word from Mr. Foe. Eventually, Susan and Friday move into Foe’s abandoned home, which soothes Susan spirits. In her letters, which are no longer dated, Susan muses that her life in England is just as boring and unchanging as her life on the island was. With little else to think about, Susan begins to enjoy being able to order Friday around so easily—his silence makes him submissive.
A young girl has started silently watching Mr. Foe’s house all day. At first, Susan assumes the girl is a messenger from either the bailiffs or Foe himself, but this proves not to be the case. To Susan’s shock, the girl claims her name is also Susan Barton—she says she is Susan’s long-lost daughter from Bahia. Susan is adamant that the girl is not her daughter, since she could never fail to recognize her daughter. Nevertheless, the young girl continues to insist that Susan is her mother, inventing a whole family backstory that has nothing in common with Susan’s real life. Susan decides that Mr. Foe, wanting to add tension and resolution to her narrative, is responsible for this familial confusion, and she declares the girl “father-born.”
Susan begins to despair, tiring of her silent companion and her endless routines. Fearing that Mr. Foe is dead, Susan wonders if she can write her story herself. But now she begins to understand why Mr. Foe was so desperate for some form of invented excitement in the tale: there is so little to write about. To enliven her narrative, Susan pays new attention to the island’s “mysteries”—Cruso’s obsession with the terraces and the backstory of how Friday lost his tongue. Susan also recalls a long-ago morning when Friday paddled out onto the ocean and scattered petals near where his ship had been wrecked.
Back in the house, Friday has started wearing Foe’s robes and wigs and dancing wildly. In her letters to Foe, Susan starts to wonder if Friday really was a cannibal, and she even pictures him eating human flesh. One day, she finds a case of recorders, and she and Friday play music together—the same six-note song Friday played during Cruso’s fever. But soon enough, Susan finds the song repetitive, and she tires even of that.
More time passes, and Susan and Friday embark on a journey to Bristol. The journey is difficult: two traveling soldiers almost assault Susan, and no innkeeper will take them in because of their bedraggled appearance. Along the way, Susan sees a dead baby, and she thinks that Friday might want to eat the baby—or even devour Susan alive. When the pair arrives in Bristol, Susan tries to put Friday on a ship back to Africa (though she has no clue where he is actually from). But she sees that all the captains who offer to take Friday will sell him back into slavery, and so, dejected, she and Friday return to London.
At long last, Susan and Friday reunite with Mr. Foe at his new London lodgings. Foe is working on the book, but he wants the focus to be on Susan’s daughter and her time in Bahia. Susan refuses, even when Mr. Foe brings the young girl to his home, attempting once more to convince Susan that this is her daughter. Susan and Foe argue about who gets to pick and choose what goes in the book, and Susan realizes that “he has the last word who disposes over the greatest force.” One night, Susan and Foe have sex, and it reminds Susan of her encounter with Cruso.
Foe points out that the ship Cruso and Friday were on was almost certainly a slave ship— and that Cruso was likely a slaver. He says Friday was probably spreading petals on the water to honor the enslaved men and women lost to the shipwreck. Moreover, Foe sees Susan’s unwillingness to understand Friday’s perspective as “a slaver’s stratagem,” and he demands that she teach Friday how to write. Susan quickly grows frustrated, but Foe insists that Susan must teach Friday a new letter every day, and he gives Friday some of his own writing papers.
Suddenly, Susan’s linear narrative breaks down, and the story begins to flash back and forth between Daniel Defoe’s house and the underwater skeleton of Cruso’s ship. An unnamed narrator—is it Susan?—swims into the shipwreck, where she sees Friday sitting. The unnamed narrator notices that there is a scar around Friday’s neck. The narrator forces Friday’s mouth open, and a slow stream comes from his lips. “Soft and cold, dark and unending,” the narrator reflects, “it beats against my eyelids, against the skin of my face.”
