The Magic Labyrinth
Philip José Farmer
 The book begins from the point of view of The Mysterious Stranger, also known as X, the renegade Ethical who has been contacting people in the valley and enlisting their aid. He had posed as the engineer Barry Thorne on the airship Parseval where he had murdered Milton Firebrass and several others, all of whom were fellow Ethicals. He is now posing as a Mayan named Ah Qaaq and is traveling in the company of the Chinese poet Li Po. Through his internal reverie he reveals some of his secrets. His identity had been discovered by Monat Grrautut, who was the director of the Riverworld project. Monat had recalled him to the Dark Tower to be judged. However, he used a remote command to kill all the inhabitants of the tower and stopped the resurrections so that agents in the valley could not return to the tower. Stuck in the valley like the others he began to make his way upriver, hoping to catch a ride on one of the riverboats. His reverie ends on one of the most traumatic days on the Riverworld. On that day the left bank grailstones fail to fire. They had done so once before, when the meteorite which Sam Clemens discovered, broke the circuit which powered them. That time the damage had been repaired by the Ethicals. But this time they are all either dead or stuck in the valley. One day after the grailstones fail the inhabitants of the left bank invade the right en masse, half of humanity dies in the conflict. At the same time Richard Burton and his friends have joined the crew of King John's ship the Rex Grandissimus. They participate in the defense of the boat after the grailstones fail and Burton, masquerading as a Dark Age British warrior, eventually becomes King John's security chief. One day Tom Mix, Jack London, and Peter Jairus Frigate apply to join the crew. Burton, recognizing Frigate, attacks him. Realizing his mistake Burton eventually becomes friendly with Frigate and becomes an ally of Mix and London. The false Frigate has disappeared, but his travelling companion, Monat Grrautut, has boarded Sam Clemens' ship. Shortly after boarding, Monat is murdered by the renegade Ethical. Eventually the two riverboats reach Virolando, a wide lake which is the last inhabited stretch before the headwaters. It is also home to the pacifist Church of the Second Chance, where Hermann Göring has become a priest. King John and Clemens finally get to square off. Initially they begin with an aerial dog fight. When the planes are destroyed the two great riverboats attack each other. In the ensuing conflict both riverboats are sunk, most of the crews die, and the two captains are killed. King John is killed by Clemens and Clemens dies of a heart attack after being pulled from the water by his mortal enemy Erik Bloodaxe. Clemens dies before he notices that Bloodaxe has become an adherent of the Church of the Second Chance, and seeks no revenge against Clemens. Among the survivors are Burton, Frigate, Alice, Kaz, Joe Miller, Li Po, Ah Qaaq, and Nur ed Din. They are joined by the American piano player Tom Turpin, the English novelist Aphra Behn, a man claiming to be Gilgamesh, and the French soldier Jean Marcelin, Baron de Marbot. They take one of the ship's launches, the only craft to survive the fight, and proceed upriver. They scale the waterfall at the end of the river and make their way, after much difficulty, to the polar sea. When they arrive at the tower they unmask Ah Qaaq as the renegade Ethical and take him prisoner. He explains his identity as Loga, son of King Priam of Troy. Like all children who died before age five, he was resurrected centuries ago and raised by the alien Ethicals to be one of their agents. He reveals also the purpose of the Riverworld. It is meant as a grand moral test, to allow humanity to progress to the point where they can achieve enlightenment. When the project is brought to a close the souls of those who have not achieved enlightenment will be set loose to wander the universe aimlessly. Loga became obsessed with sparing his earthly family this fate and worked to sabotage the project. He was the one who awakened Burton prematurely, recruited Clemens and the others, and he used satellites to direct the meteorite to land near Clemens. While this is all being revealed they discover that there is a problem with the computer which runs the tower. A part malfunctioned, and since no one was around to repair it the problem has reached a critical point. If nothing is done the computer will die, releasing all the stored wathans, or souls, of the people who died on the Riverworld. Without the wathans these people can never be brought back to life. In addition, Monat has locked out other users from accessing the computer. Göring, who had followed the group to the tower, attempts to fix the computer, but is killed by security measures put in place by Monat. Alice then devises a way to get around this programming, and deactivate the security. Loga then is able to repair the computer.