Thirty billion people from throughout Earth's history have been resurrected along the great an winding waterways of Riverworld. Most began life anew - accepting without question the sustenance provided by their mysterious benefactors. But a rebellious handful burned to challenge the unseen masters who controlled their fate Now, these adventures of Riverworld have penetrated the great tower which rises from the amazing planet's north polar seas - and within it is the mighty computer which controls the resurrection of billions of human beings. It is inside this giant tower that Sir Richard Burton, Alice Liddell Hargreaves, Peter Frigate and Li Po meet their greatest challenge - and their deadliest foe. The incredible secret behind the Riverworld is about to be unveiled . . .