God unexpectedly withdraws all of the People's agents from Earth's galaxy, abiding by the rules of the Treaty, but the angel Clarence suspects that these are more than merely precautionary measures. Before leaving he tries to convince Bernice to come to the Worldsphere with him, but as he doesn't know exactly what the danger is she chooses to remain on Dellah. She does remain suspicious of God's motives, however; neither she nor Clarence have yet figured out why God remade him in the image of a religious icon from a forbidden galaxy, especially since the People have no gods of their own except for the one they built themselves. Clarence departs from Dellah, and soon afterwards, fifteen people are found horribly slaughtered on a passenger liner, with no sign of the killer...
In the following weeks the University experiences an upsurge of religious sentiment, and the god Maa'lon is seen walking amongst his people, the Hut'eri. Benny's friend, the Reverend James Harker, is unnerved by the stories, as he'd always assumed Maa'lon's teachings to be metaphorical. A party of Grel arrive on Dellah to seek the facts behind the stories of gods walking, and Benny and Harker agree to accompany them to the home of the Hut'eri. Before leaving, Benny asks Emile Mars-Smith to look into the murders on the passenger liner; occult symbols were painted on the walls of the liner in the passengers' blood, and as a former cult member, Emile may be able to provide an insight into the killings.
Braxiatel becomes concerned when he learns that the Sultan of Tashwari is forming a "New Moral Army", which is cracking down on immoral activities across campus and demading that all students and faculty join a religion -- any religion. Furthermore, Braxiatel's people order him back home and recall his travelling machine when he refuses to leave Dellah, and the mysterious smoking man named John who warned Benny about the trouble on Dimetos reappears with dire warnings which he can't explain -- other than to say that if Braxiatel believes what's happening, that will make it all the more dangerous. At John's suggestion, Braxiatel sends the New Moral Army recruiters to the home of his friend Renee Thalia, the sole follower of the Church of the Grey. She is forced to enlist when they threaten to cut off her salary, and is furious when she learns that Braxiatel put her in this position in the hope of getting news from the inside.
Benny, Harker, and the Grel find that Maa'lon does indeed walk among the Hut'eri, and is just as warm and loving as the stories claim. He forgives Harker his doubts, and Harker pledges his life to the god without a second thought. Benny, however, feels that if possible Maa'lon is providing his followers with too much proof of his divinity, and shares her musings with the equally doubtful Grel Shemda. An outlying Hut'eri settlement is then attacked by the N'a'm'thuli, an offshoot of the Hut'eri race who worship a bloody god of death and vengeance. After the brutal slaughter of Hut'eri
children, Maa'lon sadly concludes that the N'a'm'thuli have strayed too far from the path of light and must be taught a lesson. Harker gladly joins the Hut'eri as they prepare for war.
Back at the University, the New Moral Army continues to grow in strength, and the Sultan passes a decree announcing that all under his authority must join a religion of their choice or face the "ultimate sanction". People begin to take the decree more seriously when a student is stoned to death for apostasy and a Jewish professor is burned at the stake for working on a Saturday. The most attractive religion turns out to be Renee's; the Church of the Grey was founded by those who believed that the aliens of abduction legend would one day reveal themselves and bring enlightenment
to humanity, and until that day comes, the Church encourages its followers to think for themselves and make up their own minds about what to believe. Renee thus ends up converting several hundred people who have no choice but to join a religion or die, and is promoted to Captain for her devotion to her religion. Braxiatel, accepting his error in manipulating her, tries to rescue her from the Army, but she now has no intention of leaving.
Emile, simultaneously trying to join a religion and discover the cause of the slayings on the passenger liner, is approached by Adnan, an attractive leader of an occult coven. Once Emile joins their ranks, bringing their number to thirteen, the coven is able to tap into the powers surrounding them and summon a demonic imp. Nobody is willing to pay the price the imp demands for its services, however. Emile eventually has a flash of insight thanks to a chance remark from a friend, and realizes that the murders were committed by one of the passengers on the liner -- a depressed policeman from Tyler's Folly. Needing more information, he breaks into Adnan's room to steal the grimoire, but Adnan catches him -- and reveals that he only approached Emile because the auguries had said Emile would join the group, not because he was attracted to him. Adnan allows Emile to take the book, since he was willing to risk his life for it, thus paying the ultimate price for knowledge -- a tenet of Adnan's religion.
Back on the Worldsphere, Clarence is contacted by a remote drone from the ship B-Aaron, which has learned that the evacuation of Earth's galaxy is being referred to as "Operation Ragnarok" -- a reference to the death of gods. They attempt to investigate, and learn that Dellah was chosen for a particular purpose since its native population only worshipped inanimate forces; unfortunately, the imprisoned entities were able to twist those religions to suit their own purposes. Clarence confronts God, who admits that Benny's chances of surviving the changes to come are negligible at best, and Clarence realizes that if she dies he will spend the rest of his very long life missing her.
Benny and Shemda accompany the Hut'eri army to the lands of the N'a'm'thuli despite their doubts about Maa'lon's divinity -- doubts which are not shared by James or the Grel Master. Upon discovering scores of mutilated bodies in the N'a'm'thuli territories, the Hut'eri's anger grows until they finally fall upon the N'a'm'thuli hordes and battle is joined. Their faith appears to grant them all superhuman strength, but as they fight their way through the N'a'm'thuli towards their dark nameless god, Benny and Shemda notice Maa'lon observing the slaughter with a smile on his face. Just as James is about to kill the nameless god of the N'a'm'thuli, Maa'lon announces that this was all a test to see how far his followers would go in the name of their belief, and that the god of the N'a'm'thuli is an aspect of himself as well. The belief of his followers is unshakeable, and he orders them to kill the unbelievers. Benny and Shemda flee, and hide in an abandoned underground temple as the Hut'eri and N'a'm'thuli search for them.
Braxiatel realizes that things have gone too far when the University board refuses to stand up to the Sultan's decree. He goes to John for advice, and John is appalled when Braxiatel casually mentions that he sent Benny to investigate the appearance of Maa'lon. John rushes off to rescue her while Braxiatel leads the surviving academics to the spaceport, to evacuate while they still can. Emile, meanwhile, uses the grimoire to summon the imp and strike a bargain with it, and learns that the Tyleran policeman, having awoken his own god's brethren, has returned to the spaceport to blow it up and trap more potential followers on Dellah. The spaceport security guards won't listen to Emile, but he finds Braxiatel and warns him of the danger. Together they use the grimoire to broadcast Emile's own fear into the crowd, thus evacuating the spaceport. Emile remains behind to find and defuse the bomb, but fails -- and, trapped with the bomb about to go off in front of him, he must keep his bargain with the imp.
Shemda informs Benny that there are 512 major religions on Dellah, all of which sprang into existence within the space of a century three thousand years ago, and all of which regard the gods as originating from beneath the surface of the world. Believing that the hunt has died down, Benny and Shemda emerge from the temple only to be trapped between their pursuers and the worshippers of the god Anoouki -- who has also appeared to his people. Maa'lon gives them one more chance to worship him, but Benny has finally realized what the "gods" really are -- and much more besides. Just as James is about to kill Benny, John arrives, and the gods find that they have no power over him; he simply isn't afraid of them, knowing they are parasites who feed off their followers' belief, twisting their minds and disposing of them when they are of no further use. John sends Benny and Shemda to safety, but as they depart Maa'lon decides that John is bluffing and is in fact frightened of their power. John's fear gives Maa'lon the hold he needs to control his mind, and he psychosomatically splits open John's skin and bursts both of his hearts. The Grel Master then uses his data link to his orbiting spacecraft to shoot down Benny and Shemda's skimmer before it can reach safety.
Braxiatel attempts to lead the refugees to a safe point designated by John, but Renee and her followers pursue them with orders to arrest them and kill Braxiatel. Having been told that her god will appear to her if she carries out her orders, Renee places Braxiatel before a firing squad, and waits. The Grey arrives to support her actions, but Renee unexpectedly reveals that, following First Contact, the Church amended its tenets; the Grey is an ideal, not a real alien, to be sought and not found. Before the Grey can react, Renee and her followers turn their weapons on it and blast it to ash. Thus having escaped the New Moral Army, they release Braxiatel and accompany the refugees to their destination -- a fleet of ships assembled by John to evacuate the people of Dellah. The Sultan's troops eventually realize what's happened and pursue them, and the fleet is forced to take off -- and Braxiatel is forced to abandon Benny.
Having crashed their shuttle short of the fleet's landing site, Benny and Shemda are once again menace by a god who demands their worship, but this time they are rescued by Clarence and B-Aaron. The god's worshippers are transfixed by the sight of an angel, and their temporary confusion combined with B-Aaron's shielding enables Clarence to fly Benny and Shemda to safety. Clarence admits what Benny had already guessed; the gods on Dellah are the former gods of the People. After they were expelled from the Worldsphere, God genetically engineered the psychic need for gods out of the People's mindset to prevent them from returning. The gods were imprisoned within Dellah because its native religions were based upon the worship of natural forces, but they were able to twist those religions to suit themselves, and due to the Treaty God was unable to keep as close to the situation as he had hoped. And once the gods escaped, he pulled his people out, and left the natives to fend for themselves.
Benny realizes that all the time she thought God was interested in her, he was just using her presence as a gambit to keep an eye on Dellah. She and Clarence now understand that God made him in the form of an angel in anticipation of this day, as demonstrated by the effect of his appearance upon the god's worshippers. But as the gods continue to grow in strength, even Clarence may not be enough to shake their followers' belief. Shemda locks the Grel Master out of the ship's systems and launches a buoy which will warn other Grel away from the planet. The escape fleet quarantines Dellah, cutting it off from the rest of the galaxy; perhaps confining the gods to a single world will be enough. But on one of the ships, a changed Emile is searching for believers...