Astronaut Walter Franklin, as a result of an accident, is forced to leave his job forever and return to Earth. His new profession is what he learns next: junior caretaker of a whale sanctuary—or, more simply, a shepherd of a herd of whales. The ocean, after all, is like outer space: thousands of secrets are hidden in its depths, and the engineering problems that lie before humankind in learning to master it are no less complex than the challenges of navigation, piloting, and docking…