Haalmar Evantict spread his father's last notebook across the reading table and understood he was already lost. The old scholar had died before naming which archive halls he'd combed and which still held the answer. Twelve halls stood under the city. Guessing wrong meant a year spent rereading shelves his father had already emptied. Haalmar had been circling this problem for three months. He pushed his hair back from his face and stared at a margin note in his father's cramped hand: a half-drawn spiral, no caption. It meant something. It meant nothing to him. The reading room door banged open. Haalmar turned and saw his twin sister for the first time in six years. Haalie Evantica stood in the doorway in white fur and travel dust, ponytail still wet from snow. A saber-toothed cat pressed against her hip, its coat pale blue, snowflake markings shimmering along its ribs. The cat's amber tusks nearly reached Haalie's knee. The library aide behind her had gone very still. "Move your elbow," Haalie said. "You're covering the part that matters." Haalmar didn't move. "You came back." "Mother wrote me. She said you'd been down here since the funeral." Haalie crossed the room and set one gloved hand on the notebook. The sabercat sat without being told. "You've been guessing where he searched." "I don't have his list. He never kept one." "He kept one." Haalie tapped the spiral in the margin. "He kept it in us. He taught me the other half before he sent me north." Haalmar felt something cold slide down his back. "The other half of what." "The reading method. You got the books. I got the mind work." She met his eyes. "He couldn't tell you because you weren't ready. He couldn't tell me because I left. He thought he had more time." Haalmar closed the notebook. "Show me." Haalie knelt beside the sabercat and rested her forehead against its. The cat's eyes half-closed. A minute passed. Haalmar heard nothing, but he watched his sister's mouth tighten the way their father's used to when he found a passage he'd been hunting. She stood. "He searched the four upper halls and the salt hall. He gave up on the salt hall last. He never went below the salt hall because the stair was sealed after he was denied access." "How can you know that." "Because he told her." Haalie's hand rested on the sabercat's shoulder. "He talked to her the last winter. She remembers in pictures. I can read them." Haalmar looked at the cat. The cat looked back with steady, patient eyes. "Then we don't guess," he said. "We go to the sealed stair." Haalie almost smiled. "That's the next problem. Getting through it." Haalmar stood and gathered the notebook. Six years of dead ends had ended in one minute. The wrong halls fell away. A locked door took their place.

The sealed stair stood at the end of the salt hall, a slab of dark stone set flush with the wall. Haalmar pressed his palm against it. No seam. No keyhole. He tried his father's old archive key anyway and felt the metal skid off like it had struck glass. Haalie watched from three paces back, one hand on her sabercat's shoulder. "It won't open from this side," she said. "He tried. She remembers him trying." Haalmar stepped back. "Then we don't open it from this side." Haalie's brow lifted. He tapped the notebook against his leg. "Father wrote a margin note about a spiral. I thought it was a symbol. I think it was a route. The old keeps and the cat king's castle share tunnels under the city. If the archive was built in the same season, the lower levels connect to those tunnels too. We go under. We come up inside." "That is a long walk on a guess." "Then we ask someone who knows the tunnels." They rode out before dark and reached the cat king's hall by lantern light. King Obsidian Nightwhisker met them himself, small and black and still, green eyes steady above a purple robe. He had helped their father once and never forgotten it. He listened without moving while Haalmar laid out the plan. "The archive foundations touch our lower run," the king said. "One door. It has not been opened in my lifetime. I will take you as far as the door. What is on the other side is your family's business." He tipped his head. "Your father asked me the same question, a year before he died. I told him yes. He never came." Haalmar's throat tightened. "He ran out of time." "Then do not," the king said. They walked for hours. The tunnel smelled of cold stone and old water. The sabercat led. At last the king stopped at a low iron door and stepped aside. Haalie put her shoulder to it. The hinges gave with a dry cough. Beyond was not the lower archive. It was a small dry room, shelves on three walls, a single reading stand at the center. One book lay open on the stand as if someone had set it down and meant to return. Haalmar crossed to it. The script was a language he did not know. The diagrams he did. A jaw. A skull opened in layers. Surgical tools drawn to scale, each one labeled in the lost hand. He knew the three medical records that named this book. His father had copied their citations into the front of every notebook for four years. "Haalie." His voice came out thin. "It's the surgical one. The first gap." She came to stand beside him. "He was closer than he knew." Haalmar closed the cover. The room held more shelves. Every shelf held books. None of them were catalogued anywhere above.