When 12 year old Tommy Tiller is told he and his family are leaving behind their comfortable Chicago lifestyle for an indefinitely long voyage at sea, he is shocked. Expecting nothing but monotonous days stuck with his annoyingly precocious sister Caroline, Tommy reluctantly sails away into Lake Michigan bound for the Atlantic Ocean on a 46 foot Sloop. He soon discovers, though, that often the most exciting parts of life come with the uncharted territories...