On January 29, 1873, the Pilgrim schooner-brig, equipped for whaling, sailed from the port of Oakland, New Zealand. On board are the brave and experienced captain Gul, five experienced sailors, a fifteen-year-old junior sailor - an orphan Dick Send, a ship cook Negoro, as well as the wife of the owner of the Pilgrim James Weldon - Mrs. Weldon with her five-year-old son Jack, her eccentric relative, whom everyone calls “ cousin Benedict, "and the old Negro nanny Nan. A sailboat holds its way to San Francisco with a call to Valparaiso. After a few days of sailing, little Jack notices in the ocean the Waldeck ship tipped over on its side with a hole in the bow. In it, sailors find five emaciated blacks and a dog named Dingo. It turns out that the blacks: Tom, a sixty-year-old man, his son Bat, Austin, Acteon and Hercules are free U.S. citizens. Having completed work on a plantation contract in New Zealand, they returned to America. After the collision of Valdek with another ship, all crew members and the captain disappeared and they were left alone. They are transported aboard the Pilgrim, and after several days of attentive care for them, they completely regain their strength. Dingo, according to them, the captain of "Valdeka" picked up off the coast of Africa. At the sight of Negoro the dog, for some reason, begins to growl fiercely and expresses its readiness to pounce on him. Negoro prefers not to show his eyes to the dog, who, apparently, recognized him.

A few days later, Captain Gul and five sailors, who dared to embark on a boat to catch a whale, which they noticed a few miles from the ship, die. Dick Send, remaining on the ship, assumes the functions of captain. Negroes try to learn sailing craft under his leadership. For all his courage and inner maturity, Dick does not possess all navigational knowledge and can navigate in the ocean only by compass and lot, which measures the speed of movement. He does not know how to find a location by stars, which is what Negoro uses. He breaks one compass and imperceptibly changes the readings of the second. Then disables the lot. His machinations contribute to the fact that instead of America, the ship arrives at the shores of Angola and throws it ashore. All travelers are safe. Negoro quietly leaves them and leaves in an unknown direction. After some time, Dick Send, who set off in search of a settlement, meets an American Harris, who, being in collusion with Negoro, his old acquaintance, and assuring that the travelers are on the shores of Bolivia, lures them a hundred miles into the rainforest, promising shelter and caring for his brother's hacienda. Over time, Dick Send and Tom realize that they were in an unknown way not in South America, but in Africa. Harris, having guessed about their insight, hides in the forest, leaving the travelers alone, and goes to a pre-arranged meeting with Negoro. From their conversation, it becomes clear to the reader that Garris is engaged in the slave trade, Negoro was also familiar with this craft for a long time, until the Portuguese authorities, where he came from, sentenced him to life imprisonment for such activity. After staying on it for two weeks, Negoro fled, got a job on the Pilgrim and began to wait for the right occasion to get back to Africa. Dick's inexperience played into his hands, and his plan was executed much earlier than he dared to hope. Not far from the place where he meets with Garris, there is a caravan of slaves who goes to Kazonda to a fair led by one of their acquaintance.A caravan camps ten miles from the location of travelers on the banks of the Kwanzaa River. Knowing Dick Senda, Negoro and Garris correctly assume that he will decide to bring his people to the river and go down to the ocean on a raft. There they are supposed to grab them. Having discovered the disappearance of Garris, Dick realizes that a betrayal has occurred, and decides to reach the larger river along the bank of the stream. On the way they are overtaken by a thunderstorm and a fierce rain, from which the river overflows and rises several pounds above the ground. Before the rain, travelers climb into a deserted termite, twelve feet high. In a huge anthill with thick clay walls, they are waiting for a thunderstorm. However, having got out of there, they are immediately captured. Negroes, Nan and Dick join the caravan, Hercules manages to escape. Mrs. Weldon with her son and cousin Benedict are taken in an uncertain direction. During the journey, Dick and his black friends have to go through all the hardships of going with a caravan of slaves and witness the brutal treatment of soldier-guards and overseers with slaves. Unable to withstand this transition, old Nan perishes on the road.

A caravan comes to Casonda, where slaves are distributed among the barracks. Dick Sand accidentally meets Harris and, after Harris, deceiving him, reports the death of Mrs. Weldon and her son, desperately grabs a dagger from his belt and kills him. The next day, a slave fair should be held. Negoro, who has seen from afar the scene of the death of his friend, is asking for permission from Alvets, the owner of a slave caravan and a very influential person in Casonda, as well as from Muani Lung, the local king, for permission to execute Dick after the fair. Alvets promises Muani-Lung, unable for a long time to do without alcohol, a drop of fire water for every drop of white man’s blood. He prepares a strong punch, sets it on fire, and when Muani-Lung drinks it, his completely alcoholized body suddenly lights up and the king decays to the bone. His first wife, Queen Muan, arranges a funeral, during which, according to tradition, the tsar’s numerous other wives are killed, dumped in a foundation pit and flooded. In the same pit is located and tied to a pole Dick. He must perish.

Mrs. Weldon, with her son and cousin Benedict, meanwhile, also lives in Casonda behind the fence of the Alvec trading post. Negoro holds them hostage there and wants to receive a ransom of one hundred thousand dollars from Mr. Weldon. He forces Mrs. Weldon to write a letter to her husband, which should contribute to the implementation of his plan, and, leaving the hostages in the care of Alvec, is serving in San Francisco. One day, cousin Benedict, a passionate insect collector, chases a particularly rare ground beetle. Pursuing her, he imperceptibly for himself through a mole hole, passing under the walls of the fence, breaks free and runs two miles through the forest in the hope of still catching an insect. There he meets Hercules, who has been with the caravan all this time, hoping to help his friends with something.

At this time, a long, unusual rainfall for this time of year begins in the village, which floods all nearby fields and threatens to leave residents without crops. Queen Muan invites sorcerers to the village to drive the clouds away. Hercules, having caught one of such sorcerers in the forest and dressed in his outfit, pretends to be a mute sorcerer and comes into the village, grabs the amazed queen by the hand and leads her to the Alvets trading post, There he shows with signs that the white woman and her are to blame for the troubles of her people child. He grabs them and takes them out of the village. Alvets tries to detain him, but yields to the onslaught of savages and is forced to release the hostages. After eight miles and finally freed from the last curious villagers, Hercules lowers Mrs. Weldon and Jack into the boat, where they are amazed to find that the sorcerer and Hercules are one person, they see Dick Senda, saved by Hercules from death, cousin Benedict and Dingo. All that is missing is Tom, Bath, Acteon and Austin, who had been sold into slavery even earlier and stolen from the village. Now, travelers finally have the opportunity to go down to the ocean in a boat disguised as a floating island. From time to time, Dick goes ashore to hunt.After a few days of the journey, the boat swims past the cannibal village located on the right bank. The fact that the river is not floating an island, but a boat with people, the savages discover after it is already far ahead. Unbeknownst to travelers, savages along the shore chase the boat in the hope of prey. A few days later, the boat stops at the left bank, so as not to be dragged into the waterfall. Dingo, having barely jumped ashore, rushes forward, as if sensing someone's footprint. Travelers stumble upon a small shack in which already whitened human bones are scattered. Near the tree, two letters “S. AT.". These are the same letters that are engraved on the Dingo collar. Nearby is a note in which its author, the traveler Samuel Vernon, accuses his guide Negoro of mortally wounding him in December 1871 and robbing him. Suddenly, Dingo breaks off, and a scream is heard nearby. This Dingo clung to the neck of Negoro, who, before boarding the ship to America, returned to the scene of his crime in order to get the money stolen from Vernon from the cache. Dingo, whom Negoro wounds with a knife before his death, dies. But Negoro himself is unable to escape retribution. Fearing on the left bank of Negoro's satellites, Dick is sent for reconnaissance on the right bank. There arrows fly into him, and ten savages from the village of cannibals jump into his boat. Dick shoots the oar and carries the boat to the waterfall. Savages die in it, but Dick, who took refuge in a boat, manages to escape. Soon, travelers get to the ocean, and then without adventure arrive on August 25 in California. Dick Send becomes the son of Weldon's family, by the age of eighteen he is completing hydrographic courses and is preparing to become captain on one of James Weldon's ships. Hercules becomes a great friend of the family. Mr. Weldon redeems Tom, Bath, Acteon, and Austin from slavery, and on November 15, 1877, four Negroes, having rid themselves of so many dangers, find themselves in the friendly arms of the Weldons.