Wolf Larsen, captain of the Ghost, a sealer bound for the waters north of Japan, is notorious for his cruelty. As Larsen is preparing to sail from San Francisco on what proves his last voyage, there is a collision in the fog between two ferry boats, the Martinez and the Sausalito, in which the former sinks, with nearly all its passengers lost. Among the few saved is Humphrey Van Weyden, a gentleman of leisure, who is borne out to sea by the tide. He is rescued by the Ghost, and is brought face to face with the Sea Wolf. To Van Weyden, Larsen's enormous physical strength and ruthless cruelty are appalling. Later he sees in him the strange paradox, the Sea Wolf who rends and tears, and Larsen, the eager student and embittered dreamer. Between the two springs up an odd companionship. They read poetry and philosophize together, and Humphrey tends him whenever Larsen is stricken with the torturing headaches and temporary blindness which at times overwhelm him. But his crew both fear and hate him. Leach, a green hand, tries to kill the Sea Wolf by throwing a knife at him, but missed. Desperate, Leach runs to Johnson, another sailor. They creep upon Larson as he stands by the rail with Johansen. In the struggle Larsen and Johansen are thrown overboard. The latter is drowned, but Larsen seizes the log line and climbs aboard. With characteristic disregard of consequences he goes directly to the forecastle, to find who assisted Leach in the attack. Larsen tries "the pulse test for feigned sleep." As he bends over French Louis, Leach gives the signal and the entire crew obey. There is a terrific struggle in the dark, and it is only by superhuman effort that Larsen shakes himself free and makes his way up the ladder, from which he emerges, cut and bleeding profusely, but victorious. Nothing can save Leach and Johnson from him now but flight, and while Humphrey, promoted to first mate, dresses Larsen's wounds, the two make their escape in one of the ship's boats. An open boat containing the survivors of the shipwrecked "City of Tokio" is picked up. One of them is a woman, Maud Brewster. Maud and Humphrey have much in common and are insensibly drawn the closer together because of their common fear of Larson's power over them. Leach and Johnson are sighted and, to the surprise of all, signal to be taken on board. The "Ghost" approaches very near and the Wolf grimly promises Humphrey not to lay hands on them. Nor does he. The "Ghost" sails by and the men perish. Mugridge, the cook, is too slovenly to be longer endured, and with Larsen's permission, he is tied to a rope and thrown overboard for a ducking. The men's enjoyment is changed to horror as a shark's fin cuts the wake of the ship. Wolf is first at the rope, hauling in, but in spite of their efforts Mugridge's foot is bitten off. Later the shark is caught and hung up in the rigging, to Maud's disgust. Every day adds to her fear of Larsen, and she begs him to put her ashore at Yokohama. To her terror and Humphrey's rage, Larsen shows all too plainly his intention to keep her in his power. Soon after he seizes her in his arms, Humphrey tries to save her. Both are powerless against his great strength, but one of the blinding seizures to which Larsen is subject overcomes him, and he falls fainting. They are secure for the present. There is no real safety for them, however, on board and that night they escape in an open boat, trusting ultimately to reach Japan. Shortly after, Larsen, in his cabin, hears unusual noises on deck and gropes his way forward, to find that his brother, Death Larsen, has come on board, and that the crew are deserting his ship. It is the first time they have seen him since the seizure and they stand amazed. He is blind. Wolf is left alone on the ship. Meantime, Humphrey and Maud, on a desert island, have built two stone huts and watch anxiously for rescue. Coming out one morning, they see the "Ghost," completely dismantled. Its masts and top-hamper afloat, alongside, but with sound hull, aground near their huts. They board her, to find the Wolf, though alone, blind and shorn of his power, still defiant and unafraid. He lays a trap for them, certain that if he can get his hands on Humphrey he can kill him. But the excitement brings on another seizure, and he lies at their feet, a helpless paralytic. Even at death's door, he tries once more to destroy them, though it means his own death in a terrible way. The effort extinguishes the last spark. Wolf Larsen has finished his last voyage. Humphrey and Maud repair the old ship as best they can, and sail away. They are sighted by a revenue cutter. A new day dawns for the two brought so strangely together. Our last view of them is in the library of their new home, where Humphrey begins the book which will tell of their experiences and of Larsen, "The Sea Wolf."