But Arden was made up of more than just rock. The unicorns’ song and the rush of renewed magic seemed to momentarily blur the boundaries among the guilds of magic, and Claire could hear, only slightly less clearly, the clarion call of metal running through the soil, the green thrum of roots twisting between metals and minerals as it made a gentle promise to nurture the fibers that could be spun into warmth and protection.

Metal was in stone was in green was in cloth.

With the return of the unicorns, Arden itself had awakened, and it joined in the unicorns’ song, telling a story of all that Arden had been, was now, and could be—something brighter and stronger than any one of them could have ever possibly imagined.

Claire had an entire world of magic at her fingertips. Arden’s fate was in her hands. Her heart skipped a beat. There was no way she could do this! It was too much!

The unicorn next to her reared up, a silver scythe against a blue sky. Don’t be afraid! she proclaimed. You are not alone! Four diamond hooves stomped back on the earth, and the unicorn who had been a girl lowered her head to let her crystal horn rest on Claire’s shoulder. And all across Constellation Range, the unicorns continued their gallop toward the Citadel’s peak.

The symphony of magic swelled.

Claire, the unicorns sang, change the world!

And pushed by unicorn song, Claire did.

With her fingertips, Claire found a tendril of heat sent up from the world’s heart, a delicate breath that wove in and out of underground pools, coaxing life into even the deepest and darkest places, where nothing should have been able to exist.

You can do it, Claire. You’ve already done this before. An image of the Sand Dolphin leaped into her mind.

Claire smiled. “You mean we can do it.”

After all, Sophie had always made the world around Claire come alive. Sophie had always sparked Claire’s courage. Sophie had always been a unicorn.

And they would always be sisters.

Together, the sisters of Arden urged the tendril of heat—of magic multiplied by a thousand unicorns—toward the Citadel. With the crystal horn on her shoulder, Claire could feel the magic twisting and turning as it made its way through the ground to Starscrape Citadel and then underneath it.

It moved faster and faster, spreading like roots as it passed under one chamber of craftsmen, and Claire could hear Tiller call to Spinner call to Forger call to Gemmer to help one another against the fury of wraiths. But that wasn’t where the magic needed to go. Instead, it flowed past them and down deeper and farther to another chamber, one that could be reached only by a spiraling staircase that had been roped off, marked as forbidden. And as the magic moved, it gathered strength, swelling like a wave, and then—