Inspired by the life of the French botanist Jeanne Baret, nineteen-year-old Mary has only one great passion: botany. She loves to roam with her butterfly net and insect jar, dreaming of going on an expedition to distant lands. This is impossible for a young woman in late 18th century England. Therefore, she transforms into the male illustrator Marc Middleton, is promptly accepted into the team of botanist Sir Carl Belham, and sets sail on the Sailing Queen for an expedition around the world. An incomparable adventure begins, where Mary stands her ground as a man yet feels like a woman as she falls hopelessly in love with Carl.