Enterprising Rodney Hawkhurst dreams of the sea, inspired by the glory of Francis Drake, Her Majesty's pirate. Before the journey, he falls in love with the beautiful Phyllida and plans to marry her upon his return. Her younger sister Lisbeth is drawn to danger and adventure at sea. Dressed in her brother's clothes and using his name, she enters the ship. Soon the girl realizes that she has fallen in love with her sister's fiancé, but Rodney, appreciating her courage, has only friendly feelings for her...