Wizard takes place in 2100, seventy five years after Titan. Cirocco has become an alcoholic, apparently under the strain of being the Wizard. Gaby Plauget has picked up the slack, carrying out special projects for Gaea such as building the Circum-Gaea Highway, in return for which she gets some of the benefits Cirocco enjoys, including apparently perpetual youth.
Gaea herself is bored. She arranges for streams of people looking for miracle cures to come to her from Earth, and then sets them a task: do something "heroic" (including travel once round the circumference of the great wheel), and their wishes will be granted. This is her way of ensuring an enduring supply of entertainment, as she arranges hazards for them to overcome or die trying. When not doing this she sits in the hub with her sycophants and watches old movies.
Chris Major and Robin the Nine-Fingered are two such pilgrims. Chris suffers from psychotic episodes. Robin, member of a group of latter day witches, has a strange epilepsy that only manifests itself in gravity higher than the Moon's. With Gaby, Cirocco and four Titanides they set out on the trek. Gaby and Cirocco have a hidden agenda - they want to canvass the regional brains to try to overthrow Gaea, who they see as being irretrievably insane.
During the trip, we begin to learn what really drove Cirocco to her alcoholism. As the price for the discontinuation of the Angel/Titanide War, Gaea has made the Titanides dependent on her to have children. Only her saliva can activate the eggs they produce, so that they can be implanted in a host mother to grow. The responsibility for an entire race's survival is more than Cirocco can bear; with resignation impossible and suicide ruled out by her love for the Titanides, her only release is alcohol-fueled oblivion.
The hazards of the trip include buzz-bombs, living creatures with jet engines that live on the support cables. They attack living beings, including humans and Titanides, attempting to capture them as food, and present a particular threat to pilgrims with their barbed noses and razor-sharp wings. Slowly the journey reduces the crew, killing first one of the Titanides and then, in an attack plotted by the crazed crewmember Gene, Gaby. All are separated. Cirocco and her Titanide companion Hornpipe are left on the Rim surface, while Robin and Chris are trapped underground, with the Titanide Valiha who is not only pregnant but has been badly injured. Eventually Robin has to leave Chris to tend Valiha, and climb back to the surface for help. She finds herself in one of the Arctic cold zones of the habitat, and almost dies before being rescued.
Cirocco undergoes a complete transformation. She musters her considerable powers to rescue all the remaining expedition members. Robin and Chris go to confront Gaea, only to be told she has cured them anyway, and they can get lost. Afterwards Cirocco destroys the body Gaea was using to talk to people. This cannot kill Gaea herself, but it is Cirocco's way of resigning. Now she will not be the Wizard, but the Demon.