“I think I know,” Sena said. She jumped up and ran over to her hammock, then proceeded to pour her parents’ journals from her Hollow Pack. She frantically sifted through them. Grabbing one, she hurried back to the others. “My parents’ experiments with the seams didn’t work because they were missing an essential piece: a unicorn.”

She flipped the journal open to a page with lots of words and an illustration of unicorns. Tapping the picture, she explained, “The lore around unicorns is mysterious, but it is common knowledge that they can open any door.”

“So,” Claire said, her heart pounding. “Does that mean the unicorn is in our world?”

“Any world!” Sena beamed. Then she seemed to realize what she said, and the smile slipped off. “But we have no way of knowing where.”

“Wait a second,” Sophie whispered. “Wait a second! Wait a second!” She leaped to her feet, and Claire was momentarily reminded of a time when Sophie had excitedly come up with a brand-new way of playing checkers, one that involved all the pieces of their Monopoly set plus a gold coin Dad had brought back from his trip to Canada.

“All this time,” Sophie said, “I thought the unicorn was showing me metal, rock, thread, and plants to tell me that one of the guilds had trapped him. But that wasn’t what he was saying at all—he was giving me a map. Metal, plant, thread, stone. We need to jumble all our magics together, along with a unicorn—if we want to find him. We need a Tiller,” she said, pointing to Nett, “a Gemmer, and a Forger”—she nodded at Claire, then Sena—“and,” she placed a hand on her own chest, “me: a Spinner-slash-unicorn.”

“I don’t follow,” Sena said, sitting back down on the petal-pouf with a frustrated crunch. “My parents are a Tiller and a Forger—I doubt a Spinner or Gemmer helped them.”

“Exactly!” Sophie said. “They only had half the guilds and a unicorn, which was enough to get into the seams of the world, but wasn’t strong enough magic to get them back into this one—or into another.”

Sena’s face whitened. “You’re saying they’re trapped between worlds?”

Between worlds. Claire had thought a lot about the fireplace and chimney in Windemere and the well in Arden, but she never really thought about that long, dark space where only the ladder seemed to exist. It terrified her.

“But why did the unicorn make them go there?” Sena cried.

“Because,” Sophie said, turning to look out the tent’s window where even now they could hear the Tillers and Spinners preparing to depart. “It wasn’t safe for him to be in Arden yet. Until the guilds are willing to work together to defeat Estelle, it is too dangerous for him. And so, he went to a place that could only be reached when the four guilds were reunited.”