As a teenager, Kate Harris realized that the career she craved--to be an explorer, equal parts swashbuckler and metaphysician--had gone extinct. From what she could tell of the world from small-town Ontario, the likes of Marco Polo and Magellan had mapped the whole earth; there was nothing left to be discovered. Looking beyond this planet, she decided to become a scientist and go to Mars. In between studying at Oxford and MIT, Harris set off by bicycle down the fabled Silk Road with her childhood friend Mel. Pedaling mile upon mile in some of the remotest places on earth, she realized that an explorer, in any day and age, is the kind of person who refuses to live between the lines. Forget charting maps, naming peaks: what she yearned for was the feeling of soaring completely out of bounds. The farther she traveled, the closer she came to a world as wild as she felt within.