In the mid-1850s in Paradise Cove, Massachusetts, young Joel Shore and his childhood friend, Priscilla Crowninshield, eagerly await the return of Joel’s seafaring brothers, Mark, Noah and Matthew. Joel looks forward to sailing with his much revered eldest brother Mark who captains the Nathan Ross with Noah as his first mate, while Matthew sails on the Sea Robyn . To Joel and Priscilla’s delight, the Nathan Ross and Sea Robyn arrive in the harbor within hours of each other and the family is reunited with proud patriarch Jeremiah after a year of being apart. Although the brothers are pleased by Joel’s maturity, Mark forbids his young brother to sail with him until he is confident that Joel can take care of himself. That evening, when Priscilla and her father Joshua, who is Jeremiah's best friend, come to dinner, to Joel’s confusion, Priscilla allows Mark’s pointed attentions to her. In a private moment, Mark meets Priscilla alone and confesses that he is smitten with her. Although Priscilla is flattered, she hurries away to Joel. Unknown to Priscilla, Joshua agrees to her engagement to Mark and decides it should be announced in church the following day as a surprise. Later that night, Joel follows his brothers to a saloon and purposely provokes a fight, then pretends to have fought off the notorious “Dog-nose” Danny. Impressed, Mark declares that Joel has earned the right to sail with him. The following morning in church, the minister announces Mark and Priscilla’s engagement, stunning both Priscilla and Joel. When Mark happily kisses Priscilla, but she does not respond, he is hurt and puzzled. Soon after, the Nathan Ross is ready to set sail for the Far East. Priscilla visits Joel below deck where he makes light of the farewell. When Priscilla confides that she does not love Mark, he firmly sends her back to her fiancé. Mark is again hurt when Priscilla does not respond to his passionate farewell, and as the ship sets sail he is crushed when she does not even look toward him. Over the long voyage, Mark's pain and humiliation over Priscilla’s rejection cause him to withdraw into himself and he begins to drink heavily. Just off Cape Horn, the Nathan Ross is struck by a savage storm, and Joel forces the inebriated Mark on deck to take charge. For some moments Mark, Noah and Joel steer the ship against the storm together, but later, Noah is washed overboard by a powerful wave crashing onto the deck. After riding out the storm, Mark asks Joel to be his new first mate, angering his ambitious second mate, Finch, who vows revenge on the Shores. Upon arriving in Singapore, Joel follows Mark to a seedy saloon where Finch already has made arrangements to have the captain robbed by some local thieves. Finding Mark drunk and in the arms of a dancing girl, Joel reminds Mark to think of Priscilla, prompting the annoyed Mark to order his sailors to knock out Joel and take him back to the ship. Soon after, the native girl’s cohorts attack, rob and badly wound Mark. As the dancing girl leads Mark to her room to tend to him, Finch takes Mark’s blood stained coat back to the Nathan Ross to convince the crew that Mark is dead. Weeks later, as the ship sails into Paradise Cove, a sad Jeremiah, who recently has learned of the loss of Matthew in the sinking of the Sea Robyn , anxiously notes the half mast flag on the Nathan Ross . At the docks, Finch, who has assumed command, relates the news of Noah's death to Jeremiah and tells him that Mark was later murdered in Singapore and Joel is in irons for deserting Mark. Jeremiah insists on hearing from Joel, but his youngest son refuses to speak in front of Finch. Although frustrated, Jeremiah orders his youngest son freed. That night, Joel visits Priscilla to explain his contention that Mark is still alive, but in a deep depression over Priscilla. Joel declares that she must return to Singapore with him to find Mark and prove her affections. Joel then spirits the startled Priscilla away to the ship, where he has hired several seamen to stand against Finch and his cohorts. Weeks later, the Nathan Ross arrives in Singapore, but just as Joel is about to depart to find Mark, Priscilla confesses that she always has loved him and cannot marry Mark. Joel nevertheless insists that she honor her betrothal. Meanwhile, although nearly derelict from drink, Mark has watched the harbor every day, confident of the return of his ship. Upon spotting the Nathan Ross , Mark races to the harbor, arriving just in time to witness a fight between Joel’s and Finch’s men and an anxious Priscilla embracing the battered Joel. When Finch tells his former captain that Joel abandoned him to return to Priscilla, Mark is initially furious, but then reconciles with his brother and joins the fight against Finch’s men. Priscilla helps load rifles for Joel, Mark and their men, who finally overpower Finch’s group, but not before Finch hurls a harpoon at Mark and then falls overboard to his death. As Joel and Priscilla cradle the dying Mark, he gives them both his blessing for a happy life together.