Steadying Haani, Tiaan lifted the hedron over her head. At once she saw the coloured energy patterns of the field swirling around her like a psychedelic tornado. She drew power into the hedron and reached out. As her fingers touched the wall, it thinned, so she scored the crystal across and back. The bubble vanished with a faint tinkle and a blast of freezing air. One by one, the other cubes popped until the tunnel lay open before her. Unfortunately it was also open behind. The illusory barrier had disappeared.

Some distance along, she emerged in an open cavern of rough-hewn stone shaped like a cone standing on its base. It was strikingly different from the rest of Tirthrax, where the stone had been carefully polished and intricately decorated. The rock here looked deliberately unfinished.

The cavern was dimly lit by something circular, high on one wall. Her eyes adjusted. It was a shaft that ran up through the mountain at a steep angle. Icicles hung from its lower lip and the light was daylight, deep blue as if filtered through ice. It must be morning outside.

Moving on, she passed through a blue corona like illuminated mist, though more solid. She distinctly felt its resistance. It was one of a series of concentric coloured rings lit by the light from the upper shaft. Each ring was a deeper hue than the one surrounding it. A circle of indigo, almost black, filled the centre. Tiaan pushed through the rings and almost fell into another shaft, a continuation of the first.

Laying Haani beside it, she peered down. The shaft was a smooth bore through the rock, its sides as polished as glass. She could not tell how far it went, though wisps of dark mist coiled lazily around the walls, and in the depths it had the look of a frozen whirlpool. She wondered what it would look like if it unfroze. Taking up a chip fallen from the ceiling, she dropped it in. It clicked off the sides a couple of times, she heard nothing for thirty or forty heartbeats, and at last a frosty tinkle. The shaft was deep. It would do.