Meanwhile, Ella worked on the most important part of her and Shani's plan. In the coolest cellars, deep beneath the barracks where the prince had made his command centre, Ella had the prince's men construct huge water tanks. She kept them building night and day, and as they finished one tank she made them start on another. Ella put some more men to work filling the tanks with water, and some others still lugging sacks back and forth, adding salt to the water.

Ella kept them at it, haranguing the fearsome desert warriors and Petryan labourers until they kept their heads down and did as she said. Soon, every dark space held a tank, and every tank was filled to the brim with incredibly salty water. Ella thanked the perplexed men who had helped her and dismissed them.

Ella then retired to her chambers and spent day after day enchanting rope. Her fingers became blistered from holding a scrill, and the gloves on her hands became so familiar she often forgot to take them off. Steadily the essence Prince Ilathor had given her was depleted, until she had used almost half of it, and she had filled an entire grain silo with rope. Ella connected the separate ropes into one long line, and finally she split one end of the line into multiple strands.

Lastly, she enchanted staves of polished wood, long and sharpened like spears at one end. On each stave she left the sharpened half untouched, but the other ends she covered in tiny runes, complex matrices she had created herself, unlike anything she had ever done before. One stave was much larger than the rest, a huge pole that took six men to lift. When Ella had finished the deft rune-making on its thick shaft, all of the essence Prince Ilathor had given her was gone.

She was ready.

A day later, Ella and Shani stood on the shore of Lake Halapusa, looking out at the tiered city perched precariously on its island, when the heat of summer finally broke.

A cold wind blew from the north, howling down from the mighty range of the Elmas separating Petrya from Altura and Halaran. Clouds gathered above, and the sky grew mottled with grey and black. Ella could smell the moisture in the air, and looking at her friend, noted the way the gusts tore at Shani's rust-coloured robe.

The two women stood fast as thunder rumbled from all directions at once. Sheets of lightning crackled across the storm clouds, and it was suddenly as dark as night.

The sky roared again, the heavens opened, and rain came down.

Moments before, Ella and Shani had been hot, sweltering in the Petryan summer; now the chill air from the north and the cool rainwater washed over them, soaking them to the skin.