In 1807, twelve-year-old Andy Murphy's uncle, Captain Fred Murphy, finally comes through on a promise he made four years ago. Andy has finally been invited to be the cabin boy on his uncle's square-rigged cargo vessel, Java Sea.

From the time the ship leaves Baltimore until it returns, carrying cargo to South American ports-of-call, Andy is exposed to an entirely new world. As the adventure unfolds, daily duties such as working in the galley and learning new skills like triangulation-figuring distances with a compass and a known triangle base line-keep Andy continually on the alert. Life aboard a tall ship is very different from the farm life he left behind. Yet Andy becomes a favorite of the older crewmen, developing strong bonds of friendship with his fellow sailors.

When Captain Murphy agrees to take an English Naval Officer and his family to Halifax, Andy is presented with the opportunity for a whole new adventure that could eventually change the course of his life. Will the pull of the tide be too much for Andy to resist, or does his heart belong on the farm with his family?