In San Francisco in 1850, Captain Jonathan Clark, along with his first mate, Deacon Greathouse, and Inuit pilot, Ogeechuk, easily rescues his crew, who have been abducted by his competitor, unscrupulous seal-pelt trader Portugee. Jonathan's real rivals, however, are the Russians who have enslaved the native Alaskan Inuits and forced them to kill off the seals indiscriminately for their pelts. Jonathan brings his high-quality furs to local merchant Eben Cleggett, who agrees to help him find enough financing to buy Alaska from the Russians, thus saving both the natives and the seal population. He and his men then take over the city's fanciest hotel, which also houses Russian Countess Marina Selanova, who is on the run from a forced marriage to ruthless Prince Semyon. Her representative, Paul Shushaldin, has contracted with Portugee to sail her to her uncle, Ivan Vorashilov, in Sitka, Alaska, but Portugee now has no crew and so must cancel the deal. Marina sends Paul to Jonathan to entreat him to sail them to Sitka, but as Jonathan despises the Russians, who want to hang him for "stealing" their pelts, he refuses. Desperate, that night Marina infiltrates a party Jonathan is throwing for his men and entrances him with her beauty. She pretends to be the countess's traveling companion, and he takes her to see the city. When she reveals that she wants passage on his ship, Jonathan is initially insulted but finally agrees to her request. By the next day, they have fallen in love, and when Prince Semyon arrives to recapture Marina, she reveals that she is to be married. Jonathan ecstatically plans a lavish wedding, but is informed by the hotel's maitre d' that Marina is actually the countess, and that she and the prince left for Sitka earlier that morning. Jonathan is crushed, and soon after learns that he has used up all his credit and owes $15,000 to the hotel. He recklessly challenges Portugee to a race to the Alaskan Pribilof islands, with the other's ship as the prize. Prior to Jonathan's race, Cleggett brings him the note for $10 million for the purchase of Alaska, which the Deacon pockets when Jonathan spurns it. During the race, rough weather rages, and although Portugee's boat is faster, Jonathan's superior sailing skills prevail. Meanwhile, in Sitka, Marina repeatedly attempts to escape from the prince, who captures her and threatens to hang both Jonathan and Uncle Ivan, who is failing to make profits from the seal trade. Jonathan sails on to the islands, where the Deacon explains to young sailor William how Jonathan kills only the bachelor seals, leaving the mated seals to repopulate. Portugee arrives as they finish their collection of pelts, and Jonathan invites him aboard. Just then, the prince's gunboat appears on the horizon, and Portugee, realizing they are about to be attacked, attempts to take over the boat and steal the pelts. As the two crews fight, the prince seizes them all and brings them to Sitka as his prisoners. There, Marina visits Jonathan in the dungeon and convinces him that she was forced to leave San Francisco. The Deacon gives her the note for Alaska's purchase and she brings it to the prince, who ignores it. When he orders Jonathan flogged in front of Marina, she throws herself in front of the whip and finally agrees to marry the prince in return for Jonathan's freedom. Jonathan sets sail but turns around as soon as his ship is out of sight and sneaks back to the island just as Marina's wedding ceremony is commencing. While his men attack the prince's guards, Jonathan grabs Marina and flees. Sending her and his men on to the ship, he sets the Russian gunboat on fire. The prince traps Jonathan in the boat, but moments before the gunpowder onboard explodes, Jonathan jumps off. He swims to his ship and embraces a joyful Marina. The Deacon explains to William that, although it is true that Jonathan can now buy Alaska, he will not be interested in that as "he has the world in his arms."