When the first mate of the freight boat Neptune falls ill, it is up to Abigail, the captain's daughter, to steer the ship up the Hudson River from New Jersey to New York City.
In an effort to fulfill their dying father's last request, nine-year-old Ben and his brother and sister construct a barn on their land in the Oregon Territory.
While learning to sail during a visit to his grandmother's at the Connecticut shore, eleven-year-old Tony becomes excited about the rumors of sunken treasure in the area and starts following a couple who seem to be making a mysterious search for something.