Dreyfus laid a thick-fingered hand on Thalia's shoulder.

"Just remember you're here to do one thing – to secure evidence. Sparver and I'll take care of any other distractions."

When the elevator doors puckered open, a wave of heat and humidity hit like a hard, wet slap. Steam billowed in the air as far as Thalia could see. They were standing at the entrance to an enormous cavern hewn into the rocky torus of the wheel's rim. Much of the visible surface consisted of pools of water arranged on subtly different levels, connected by an artful system of sluices and channels. People were bathing or swimming, or playing games in the water. Most of them were naked. There were baseline humans and people very far from human. There were sleek, purposeful shapes that might not have been people at all.

Dreyfus pulled a pair of bulbous glasses from his tunic pocket and rubbed the condensation from the dark lenses onto his sleeve. Thalia followed his cue and slipped on her own glasses, taking note of the changes she saw. Many of the apparently naked people were now masked or clothed, or at least partly hidden behind shifting blocks of colour or mirage-like plumage. Some of them had changed size and shape. A few had even become invisible, although the shades provided a blinking outline to indicate their true presence. Luminous branching structures – Thalia couldn't tell if they were sculptures or some form of data visualisation related to an ongoing mindgame – loomed over the complex of pools.

"Here comes the welcome," Dreyfus said.

Something strode towards them, following a dry path that wound between the bathing pools. A pair of shapely, stockinged female legs rose to support a flat tray arrayed with drinks. High heels clicked as the legs approached, placing one foot before the other with neurotic precision. The fluid in the glasses remained rock steady.

Thalia's hand moved to her belt.

"Steady," Dreyfus breathed.