Maudie and Arthur were not only orphaned and sold to a cruel family, their father and their name was disgraced. The twins know their father didn't do what he was accused of doing and they are determined to become explorers like their father and clear his name. Maud is a brilliant engineer. Arthur loves to read and learn and discover. Of course, the children still hold hope that perhaps their father survived the expedition south. So when they get the opportunity to go on an expedition south, they jump at the chance to fulfill a life long dream and maybe even find their father, or at the very least, find out the truth of what happened on that trip.