In the far future, an indestructible and massive canal more than 2,000 miles long spans the mid-continent of Earth. Nothing can mar it, move it, or affect it in any fashion. At its western end, where it meets the sea, is an equally indestructible structure comprising three levels of seemingly empty chambers. Scientists from three different civilizations, separated in time by hundreds of thousands of years, are investigating the canal. In the most distant of these civilizations, religious rebellion is brewing.
