Shortly after his arrival up at the family cottage on Lake Superior, Stan Goobash watches in horror as a mammoth sinkhole opens in the middle of the lake. Moments later, the greatest of all the Great Lakes is nothing more than a memory. Like others, Stan is drawn across the dry lakebed to the circular chasm that has swallowed one tenth of the world's supply of surface freshwater. An avid skydiver, Stan quickly formulates a plan to get to the bottom of this mystery, or die trying. At the edge of the great sinkhole, Stan is joined by two others. They jump, but will soon learn that Lake Superior doesn't like to give up her dead.