George Washington "Wash" Black is born into slavery on Barbados. He is raised by Big Kit, another slave. When Wash is eleven, the owner of the plantation dies and the plantation is turned over to his nephew, the extraordinarily cruel Erasmus Wilde. Wash's life continues on much as it did before, until he and Big Kit are called to serve in the big house. There he meets Wilde's younger brother, Christopher "Titch" Wilde, a scientist, who enlists Wash as his manservant. Titch teaches Wash to read and cook and, after noticing he is a prodigious artist, allows him to focus on drawing. Titch and Erasmus are later joined by their cousin Philip. Philip eventually reveals to Erasmus and Titch that their father has died, leading Erasmus to hatch a plan to move back to return home for a few years, leaving Titch in charge. He furthermore refuses to sell Wash to Titch, having become aware both of how close they are and of Wash's artistic talents. While arrangements are still being made, Philip commits suicide in front of Wash. When Wash informs Titch of the death of his cousin, he realizes that Erasmus will murder Wash in retaliation for Philip's death. To save Wash, the two escape in Titch's balloon but, due to a sudden storm over the sea, Titch crash-lands onto a merchantman. There they meet the captain Bendikt Kinast and his brother, the ship's doctor Theo Kinast. Though the brothers guess that Wash is a runaway slave, they nevertheless decide to take the pair to Virginia.
In Virginia, Titch learns that his brother has hired a bounty hunter, a Mister Willard, to capture Wash. While there they also meet up with a penpal of Titch's named Edward Farrow, who is an abolitionist. While at Farrow's Titch also learns that his father may still be alive, prompting him to decide to go to the Arctic to see him. Farrow and Titch offer Wash the opportunity to escape to Upper Canada where former slaves are able to live in freedom, but Wash declines. In the Arctic, Titch discovers that his father is indeed alive, but Wash is surprised that their reunion is so cold, and Titch's father is indifferent to his sons and their disputes. Devastated by his father, Titch decides to leave the Arctic and Wash behind. Though Wash tries to follow him he is unsuccessful, and Titch disappears during a snowstorm. Mr. Wilde tries to find him, but after searching for several days he comes back empty-handed and dies of a fever. No longer under the protection of either Wilde, Wash decides to take Titch's advice and resettles in Shelburne, Nova Scotia. From the ages of thirteen to sixteen, Wash lives a life of fear, afraid that the bounty on his head will be collected. After spying some jellyfish on the docks, he remembers his interest in illustration and turns to that passion anew.
He meets Tanna, a fellow aspiring illustrator and the daughter of renowned marine biologist G.M. Goff. Wash works with Goff and Tanna to collect and illustrate marine specimens, and has the novel idea of creating an aquarium. Tanna and Wash eventually fall in love and have sex after Wash is attacked by Mr. Willard. Wash had fought off Willard's attack, knifing him through the eye, but had been injured himself. Getting word that Titch may be alive, Wash follows Tanna and Goff to London, where the three begin work on their aquarium. Wash and Tanna look for information into Wash's past life and discover that Big Kit is Wash's mother. Wash attends Willard's public hanging for murder at Newgate Prison. Wash and Tanna eventually track down Titch in Marrakesh, Morocco. In the deserts outside Marrakesh, Wash finds Titch living alone with a young Moroccan boy. Wash confronts Titch about their time together and his abandonment of Wash. A desert storm comes down upon the camp and, having received no satisfactory answer from Titch, the book ends with Wash beginning to walk off into the swirling sand.
