In 1832, an American girl who had been studying in England is sent home to Providence, Rhode Island. The ship on which she is to sail is a brig, the Seahawk, a merchant ship that will take about two months to reach Providence. Before the ship even sails, matters grow dark for Charlotte Doyle. The two families that were to keep her company both cancel their plans to sail on the Seahawk.

Twice, porters carrying her luggage bolt and run when they learn that she is to sail on the Seahawk. The man assigned to see her safely on board, Mr. Grummage, is an overbearing, insensitive man, who cares nothing about Charlotte's safety; he dumps her on the ship and departs, leaving Charlotte alone among an unhappy crew. The ship's Captain Jaggery is a madman who is obsessed with orderliness and neatness, the crew is mutinous, and Charlotte has only the rules for a young lady's proper conduct to rely on in a situation that will require all her courage and fortitude to survive.