George Washington “Wash” Black is an 11-year-old boy who has lived his whole life enslaved on Faith Plantation in Barbados. When the current master, Richard Black, dies, his nephew Erasmus Wilde takes over. Erasmus is much more brutal to the slaves than Black was: Erasmus beats them, maims them, kills them, and hires cruel overseers to do the same thing. The only person protecting Wash is Big Kit, an older enslaved woman who works in the cane fields with Wash. Big Kit considers killing Wash and herself so they can both be reborn in the African kingdom Dahomey. However, when other slaves begin to commit suicide, Erasmus vows to decapitate the dead body of any slave who does this so they cannot be reborn, and so Big Kit does not go through with her plan.
Soon after Erasmus takes over Faith Plantation, his brother Christopher Wilde (nicknamed “Titch”) arrives to conduct scientific experiments and run test flights for his Cloud-cutter, an air vehicle. Seeing that Wash is the perfect size to accompany him in the Cloud-cutter, Titch enlists Wash as his manservant. He teaches Wash to read and write and about scientific concepts. Wash particularly likes marine life, and he discovers he has a talent for sketching. Titch also is clearly uncomfortable with the way his brother treats the enslaved people on the plantation, and he tells Wash that he’s an abolitionist.
Almost a year after Titch’s arrival, his melancholy cousin, Philip, visits while Erasmus is off tending to business on another plantation. Titch shows Philip the work he’s been doing on the Cloud-cutter, and one day, the hydrogen that Titch is testing explodes in Wash’s face, leaving him with severe burn scars on the right side of his face.
After Wash recovers and Erasmus returns from the other plantation, Philip tells Erasmus and Titch that their father, Mr. Wilde, has died. He was a scientist working in the Arctic, and Titch (who adored his father) is devastated that his father will never get to see his Cloud-cutter. Erasmus is thrilled, however, as this likely means that he will get to return to England to run his father’s estate, while Titch will have to run Faith Plantation.
Some days later, Philip asks Wash to accompany him hunting while Titch is busy speaking to Erasmus. When Wash and Philip reach the base of the mountain, Philip takes his gun and shoots himself in the head, leaving Wash covered in blood. When Wash returns and explains to Titch what happened, he is terrified—he knows that Erasmus will likely have Wash killed for Philip’s death even though he had nothing to do with it. Concerned for Wash and unwilling to stay on Faith Plantation and run it, Titch decides to escape with Wash in the Cloud-cutter that night.
Flying through a storm, Wash and Titch crash into a ship headed for Virginia. Once in the United States, they discover that Erasmus has set a bounty hunter, John Willard, after Wash, with a reward of 1,000 pounds for his return—dead or alive. Titch and Wash seek shelter with Mr. Wilde’s friend, Edgar Farrow, an abolitionist who helps slaves escape to Canada. At Edgar’s home, he informs Titch that he received a letter from Titch’s father only a few weeks earlier—which would have been after Mr. Wilde died, according to Philip. Titch decides to go to the Arctic to find out what happened to his father, and though Titch offers for Wash to escape to Canada with other runaway slaves, Wash decides instead to accompany Titch.
Wash and Titch board a ship and sail to the icy Arctic, where they discover that Mr. Wilde is indeed alive. Titch recognizes that Wash is in danger as long as he is around Titch because Erasmus (and the bounty hunter) will always be near, but Wash insists that he would rather go wherever Titch goes. Burdened by caring for Wash and feeling that he has no other option, Titch arranges for Wash to stay with Mr. Wilde and his assistant, a deaf man named Peter House. Titch then abandons Wash by walking into severe snowstorm alone and with no provisions, ostensibly committing suicide. Though Mr. Wilde and Peter search for days, they are unable to find Titch’s body, and soon after Mr. Wilde grows ill and dies.
After Mr. Wilde’s death, Wash goes to Nova Scotia, Canada, to live as a free man. He still feels danger all around him, as though John Willard could appear to collect him at any moment. Over the next two years, Wash grows deeply unhappy and purposeless, and often faces beatings from white men. One day, however, he rediscovers his love for sketching, and every morning he looks for marine life at an inlet and sketches it. It is during his sketching that he meets Tanna, a beautiful mixed-race English woman whose father, Mr. Goff, is a famous marine zoologist. She asks Wash to teach her how to sketch, and she quickly expresses romantic interest in him. Wash also starts accompanying Tanna and her father to collect marine specimens, though he and Tanna have to hide their feelings for one another in front of her father. A few weeks before Tanna and Goff leave to return to work on a marine exhibit in London, Wash suggests that they make it a live exhibit and works out plans for an extravagant aquarium, hoping to impress Tanna.
A few days later, John Willard finds Wash in a local tavern and explains that he stopped looking for Wash a few years earlier when Faith Plantation closed down. He also reveals that Erasmus has died, and that he saw Titch in London recently. Willard leaves Wash stunned in the restaurant—but later that evening, as Wash walks past a dark alley, Willard attacks him. Wash is able to fend Willard off by stabbing him with a knife, and Wash staggers to Tanna’s house. Goff is away for a few days, but Tanna answers the door. After Tanna cleans up Wash’s wounds, she undoes her nightgown, and they have sex.
Knowing that Titch might be alive, Wash travels with Tanna and Goff to London. Wash also helps them with their plans for the aquarium, even though Wash knows he’ll never be credited for it. He lives in the Goffs’ garden house, and he and Tanna continue to be secret lovers. Meanwhile, Wash and Tanna look for Titch at his family’s estate in Granbourne. There, Wash doesn’t find Titch, but he does learn that Titch worked with the Abolitionist Society, and they might have more information.
At the Abolitionist Society, Wash finds records of Faith Plantation and he learns that Big Kit has died—and that she was his biological mother, which shocks and moves him. A man with the Society, Richard Solander, notes that Titch’s last letter to them came from an address belonging to Peter Haas in Amsterdam. Before Tanna and Wash travel to Amsterdam, they learn that John Willard is due to be hanged at Newgate Prison, and they attend the hanging. Wash thinks he sees Titch in the crowd, but he only imagines it.
Peter Haas turns out to be the same “Peter House” whom Wash met in the Arctic, and when Wash and Tanna travel to Amsterdam, Peter says that Titch is now living in Marrakesh, Morocco. Though Tanna is exasperated by all the traveling and Wash’s obsession with finding Titch, she accompanies him to Morocco as well.
In Morocco, Wash and Tanna find Titch trying to recreate his Cloud-cutter, assisted by a young Moroccan boy. Wash confronts Titch about why he abandoned Wash in the Arctic. Titch explains that he simply wanted to protect Wash. When Wash says that Titch never truly saw him as an equal, but as someone to save, Titch counters that he treated Wash like family, and he never wanted to mistreat Wash. Titch also explains some things from his past that haunt him: he and Erasmus bullied Philip mercilessly growing up, and so he felt guilty about Philip’s decision to take his own life. Wash realizes that Titch has no remorse for how he treated Wash, and the book ends with Wash walking off into a severe sandstorm.
