The artefact started to move, this time very slowly. They looked up, through the glass floor, and saw a bird flying over. It, too, was moving very slowly – flapping its wings at snail's pace as if it were suspended in some kind of viscous liquid. Muko pointed the bird out to the other children. None of them had any idea what was happening.
Then they noticed another passage leading away from the chamber on the other side. Just as they did so, both the entrances started to close. The children hurled themselves across the chamber and into the far passage just in the nick of time. They'd done it! The entrance closed behind them. They were now in a narrow corridor in the heart of the mountain.
They weren't in total darkness because there were some symbols which shone out brightly and showed the way they should go through the tunnel. It wasn't silent, either. They could hear a distant rumble – as if a heavy wheel were being rolled along on hard ground. There was something sinister about the tunnel.
“There's no way back now,” said Muko.