Emily (11), Christopher (9), and their younger brother Matthew (8), have no mother, yearn for their father's attention, and long to have friends. But when a trouble making boy named Henry shows up at their door one day, the children find themselves on the adventure of a lifetime aboard a real tall ship, under the watchful eye of Captain Upham, an overly eccentric ship captain. Will the children be able to outsmart the captain, return to their father, and find out the truth about their family once and for all?