The narrator, a young man named Clint Webb, recounts his voyage aboard the four-masted Gullwing, where he befriends Thankful Polk, clashes with rivals, and gains experience under Captain Bowditch. The ship joins an ocean race against a sister vessel and faces storms, a ghostly visitation, sea monsters, and the wreck of another ship, events that lead to tragedy and a narrow escape. Interwoven are episodes of rivalry, growing affection for Phillis Duane, moral tests, and a return home that settles several personal conflicts while reflecting on camaraderie, courage, and the dangers of life at sea.