In the far future, much of the world is covered with water and people live on islands. The people here use ancient technology powered by refractors. In order to survive, people called diggers search for refractors and sell them for money and/or to power their flying machines for travel. Eventually, legends of a treasure called the Mother Lode appeared. It was said that the Mother Lode had many powerful refractors and that, if discovered, it could power the world indefinitely.