They came to an arched entrance, wide enough for ten men to walk abreast and easily twelve feet tall. Two of Zara’s fellow sorcerers stood guard outside, both wearing gray robes and clutching tall staffs in their hands, and moved to the side to allow them past. Entering the dark interior, Zara led Palemon along a corridor that followed the curve of the wall, before coming to another archway, this one revealing light at the tower’s hollow core.

Palemon walked across a floor of paved stone to the very center of the shaft and looked up. He could see a small circle of blue sky, high above.

‘First, the tower,’ Zara said. She lifted her staff, indicating the shaft they were standing in. Despite being at ground level, it felt to Palemon as if he were standing at the bottom of an immense well. ‘As you can see, its basic shape is a cylinder, hollow from base to top.’

‘For viewing the sky?’

‘That is what the priests thought, although the mystery has always been: what does the circle reveal? The sun’s passage? The moon? The constellations? Every one of the dozen magi we brought with us from Necropolis made his or her own assessment. We all agree. None of those things make sense.’

Despite living in Malakai for weeks, Palemon hadn’t made time to see the tower, and he turned in a slow circle, gazing along the interior of the wall, seeing steps built into the inside of the tower and rising almost to the top of the shaft. The steps terminated at a stone ledge, encircling the shaft just below the tower’s lip.

‘What is the purpose of that ledge?’ he asked. ‘I doubt you could see anything from there.’ He tilted his head back. ‘Are those iron hoops circling the wall, just below?’

‘To be truthful, I don’t yet know the purpose of the stairway. But please, there is more. Come.’

Zara inclined her head, and he followed her back inside to the curved corridor. He was surprised to see that the path straightened and now the floor was sloping down, into the earth. The corridor, as wide as the main entrance, was steadily descending, the stone ceiling angling with it.

Palemon frowned, perplexed at the passage’s immense size. He wondered where it led, and figured they were well below street level when the tunnel abruptly terminated in a chamber. He saw objects on a table: a stand for incense, a lamp, a statue of the god Helios. The table had been pushed to the side.

Strong force had torn a hole in the rear wall.

‘It was only when I came back to the tower that I realized the stonework here was newer,’ she explained. ‘I used the power of wind to break the wall.’

Palemon tugged on his beard. The force it would have taken to tear down a wall of solid stone . . .

‘This way,’ Zara said.