Elara Greenwhisper had wanted to leave the Hidden Green her whole life, but the forest chose this morning to speak to her instead. She knelt in the wet moss beside a fallen fawn. Blood matted its leg. She pressed her palm over the wound and let her gift rise. A soft green glow spread under her fingers. The bleeding slowed. The fawn's breathing eased. Then the fawn stopped watching her. It turned its head down and stared at the ground. The earth trembled under Elara's hand. Not a shudder from her healing. Something deeper, moving in the roots below the soil. She pulled back and pressed her ear to the moss. A low hum answered, faint and old, like a voice buried alive. "What is that?" she whispered. The hum stopped. But she had felt it. Her whole life, her people spoke of the Hidden Green as a city on the surface, nothing more. No one ever mentioned a sound beneath the roots. She stood, her heart pounding, and ran to the one person who kept every old story. Elder Moss sat outside his moss-woven house, sorting dried leaves into piles. His silver beard hung with tiny braids. He did not look up when Elara's shadow fell over him. "You felt the roots," he said. Elara stopped short. "You knew." "I hoped you never would." He set down a leaf with a slow, careful hand. "There is an old thing beneath us, Elara. Hidden long before you were born. Your people buried it and sealed the way down." "Then show me the way down." His blue eyes finally lifted to hers. "There is no way down. The paths through the roots were closed. Only a Rootwalker could ever open them again, and none of them know how. That was the point." Elara's stomach dropped. She had a name already. She turned and ran again. Daisy was gathering thin roots at the forest's edge when Elara found her. Daisy was a Rootwalker, and one of Elara's oldest friends. She could feel the hidden paths beneath the soil the way Elara felt a heartbeat under her hand. "There's something under the city," Elara said, breathless. "A sealed door in the roots. I need you to find it." Daisy frowned, then knelt and pressed both hands flat to the ground. She closed her eyes. For a long moment nothing happened. Then her fingers curled. "There," Daisy said softly. "A hollow. Old roots grown across an opening." She opened her eyes, and they were wide. "I can feel the way in." The two girls dug where Daisy pointed. Roots parted under her touch like curtains. Below them yawned a dark shaft, cold air rising from its throat. Stone steps curved down into black. Elara stared into the dark she had been told did not exist. The way down was open now. And she had no idea what waited at the bottom.

The stairs fell away into black. Elara set one foot on the top step and felt cold air rise from below. She could not see the second step, or the third. One wrong move meant a long fall into the dark. She pulled her foot back. Daisy knelt at the edge, both hands still pressed to the parted roots. She would guide anyone through a tangle of roots without a second thought, but even she stared into the shaft with a tight jaw. "We can't climb blind," Daisy said. "No light. No rope." Elara reached for her healing gift, the same green glow she had used on the fawn. It flickered under her palm, then died. It mended wounds. It did not light stone. She let her hand drop. "Then we need light," Elara said. "Something that shines on its own." Daisy's eyes moved to the forest behind them. "The blue ones. They wake at night. They still glow when you hold them." She meant the moonlit butterflies that drifted through the brambles after dark. They searched the vine-wrapped fort at the forest's edge, where the brambles grew thick and old. Elara moved slow among the thorns. Then she saw it, folded on a leaf inside the fort's shadowed arch. A butterfly with wings of deep blue, each spot burning a soft, cold light. She cupped her hands around it. The glow pushed between her fingers. It did not fly. It rested against her skin and pulsed, brighter in the dark of her palms. "It won't stay," Daisy warned. "They never do." "Then we go now." They returned to the shaft. Elara opened her hands near the top step. The blue light spilled down the stone. She could see three steps. Then five. The butterfly clung to her wrist and shone. She went down. Daisy came behind, one hand on the wall. The steps curved. Each one appeared in the blue glow just before Elara's foot found it. The hum from below grew louder, a slow sound she felt in her teeth. The stairs ended. Elara stepped onto flat stone. The butterfly's light spread across a wide, dark space, and touched something ahead. Water. A still black pool stretched into the dark. A single narrow bridge crossed it, old wood with slim rails, arched over the water like a held breath. Across the bridge, the hum came from a shape she could not yet see. The butterfly's wings flared once, then dimmed. Its glow was fading. "Elara," Daisy whispered. "The light's dying. And I don't feel any roots down here. If it goes out, I can't find the way back up." Elara looked at the fading blue in her hands, then at the bridge waiting in the dark. They had reached the bottom. Now the light that carried them was running out.